I have been happily running the default KDE distribution shipped with Fedora Core 21 until this evening: now when I login and it starts launching KDE it simply stacks and freezes. When I right click the mouse on the Application or in any Xterm nothing happens, the characters I type from keyboard are not displayed, and only when I move to some other xterm and come back to the original one I can see what I typed. It is extremely slow even to complete simple commands like ls -l.
Important: the problem appears only with one user! I am the only user of this laptop. I have created another user entering as root, and I have verified that this new user does not experience any problem with KDE, everything works smooth.

I attach here the .xsession-errors file: many thanks in advance for any help/suggestion!

===========================
/bin/.: Permission denied.
access control disabled, clients can connect from any host
startkde: Starting up...
Connecting to deprecated signal QDBusConnectionInterface::serviceOwnerChanged(QString,QString,QString)
kbuildsycoca4 running...
Agent registered
Object::connect: No such signal org::freedesktop::UPower::Device::Changed()
Object::connect: No such signal org::freedesktop::UPower::Device::Changed()
Object::connect: No such signal org::freedesktop::UPower::Device::Changed()
QDBusConnection: name 'org.kde.kglobalaccel' had owner '' but we thought it was ':1.20'
kded(2762) ProfileUtils::createIccProfile: EDID ICC Profile already exists "/home/vantonuccio/.local/share/icc/edid-98d3ef32d2d51777902a4e801dc8f462.icc"
QDBusObjectPath: invalid path ""
kded(2762) ColorD::addOutput: Failed to register device: "device id 'xrandr-Chimei Innolux Corporation' already exists"
QDBusObjectPath: invalid path ""
kded(2762) ColorD::addOutput: Failed to register device: "device id 'xrandr-Chimei Innolux Corporation' already exists"
kded(2762) ProfileUtils::createIccProfile: EDID ICC Profile already exists "/home/vantonuccio/.local/share/icc/edid-98d3ef32d2d51777902a4e801dc8f462.icc"
kded(2762) ProfileUtils::createIccProfile: EDID ICC Profile already exists "/home/vantonuccio/.local/share/icc/edid-98d3ef32d2d51777902a4e801dc8f462.icc"
kwin(2816): ""fsrestore1" - conversion of "0,0,0,0" to QRect failed"
QCoreApplication::sendPostedEvents: Cannot send posted events for objects in another thread
QCoreApplication::sendPostedEvents: Cannot send posted events for objects in another thread
OpenGL vendor string: Intel Open Source Technology Center
OpenGL renderer string: Mesa DRI Intel(R) Haswell Mobile
OpenGL version string: 1.4 (3.0 Mesa 10.4.3)
Driver: Intel
GPU class: Haswell
OpenGL version: 1.4
Mesa version: 10.4.3
Linux kernel version: 3.19.3
Direct rendering: no
Requires strict binding: yes
GLSL shaders: no
Texture NPOT support: yes
Virtual Machine: no
QDBusObjectPath: invalid path ""
plasma-desktop(2826)/libplasma Plasma::isPluginVersionCompatible: unversioned plugin detected, may result in instability
plasma-desktop(2826)/libplasma Plasma::isPluginVersionCompatible: unversioned plugin detected, may result in instability
plasma-desktop(2826)/libplasma Plasma::isPluginVersionCompatible: unversioned plugin detected, may result in instability
plasma-desktop(2826): ""geometry" - conversion of "58,2,0,25" to QRectF failed"
plasma-desktop(2826): ""geometry" - conversion of "58,2,0,25" to QRectF failed"
plasma-desktop(2826): ""geometry" - conversion of "58,2,0,25" to QRectF failed"
plasma-desktop(2826): ""geometry" - conversion of "58,2,0,25" to QRectF failed"
plasma-desktop(2826)/libplasma Plasma::isPluginVersionCompatible: unversioned plugin detected, may result in instability
plasma-desktop(2826)/libplasma Plasma::isPluginVersionCompatible: unversioned plugin detected, may result in instability
plasma-desktop(2826)/libplasma Plasma::isPluginVersionCompatible: unversioned plugin detected, may result in instability
plasma-desktop(2826)/libplasma Plasma::isPluginVersionCompatible: unversioned plugin detected, may result in instability
plasma-desktop(2826): ""geometry" - conversion of "58,2,0,25" to QRectF failed"
Object::connect: No such signal org::freedesktop::UPower::Device::Changed()
Object::connect: No such signal org::freedesktop::UPower::Device::Changed()
Object::connect: No such signal org::freedesktop::UPower::Device::Changed()
========================> 7 0
static bool QDeclarativeMetaType::isModule(const QByteArray&, int, int) Qt 4.7 import detected; please note that Qt 4.7 is directly reusable as QtQuick 1.x with no code changes. Continuing, but startup time will be slower.
file:///usr/lib64/kde4/imports/org/kde/plasma/components/SectionScroller.qml:103: TypeError: Result of expression 'listView' [null] is not an object.
file:///usr/lib64/kde4/imports/org/kde/plasma/components/SectionScroller.qml:175: ReferenceError: Can't find variable: sectionsRepeater
file:///usr/lib64/kde4/imports/org/kde/plasma/components/SectionScroller.qml:103: Error: Cannot assign [undefined] to QString
file:///usr/share/kde4/apps/plasma/plasmoids/notifier/contents/ui/devicenotifier.qml:224:13: QML QDeclarativeListView_QML_63: Possible anchor loop detected on fill.
file:///usr/share/kde4/apps/plasma/plasmoids/notifier/contents/ui/devicenotifier.qml:224:13: QML QDeclarativeListView_QML_63: Possible anchor loop detected on fill.
file:///usr/share/kde4/apps/plasma/plasmoids/notifier/contents/ui/devicenotifier.qml:224:13: QML QDeclarativeListView_QML_63: Possible anchor loop detected on fill.
file:///usr/share/kde4/apps/plasma/plasmoids/notifier/contents/ui/devicenotifier.qml:224:13: QML QDeclarativeListView_QML_63: Possible anchor loop detected on fill.
file:///usr/share/kde4/apps/plasma/plasmoids/notifier/contents/ui/devicenotifier.qml:224:13: QML QDeclarativeListView_QML_63: Possible anchor loop detected on fill.
file:///usr/share/kde4/apps/plasma/plasmoids/notifier/contents/ui/devicenotifier.qml:224:13: QML QDeclarativeListView_QML_63: Possible anchor loop detected on fill.
file:///usr/share/kde4/apps/plasma/plasmoids/notifier/contents/ui/devicenotifier.qml:224:13: QML QDeclarativeListView_QML_63: Possible anchor loop detected on fill.
Object::connect: No such signal org::freedesktop::UPower::Device::Changed()
Object::connect: No such signal org::freedesktop::UPower::Device::Changed()
Object::connect: No such signal org::freedesktop::UPower::Device::Changed()
Object::connect: No such signal org::freedesktop::UPower::Device::Changed()
Object::connect: No such signal org::freedesktop::UPower::Device::Changed()
Object::connect: No such signal org::freedesktop::UPower::Device::Changed()
file:///usr/share/kde4/apps/plasma/plasmoids/battery/contents/ui/CompactRepresentation.qml:73:9: QML Column: Cannot specify top, bottom, verticalCenter, fill or centerIn anchors for items inside Column
NetworkManagerQt "plasma-desktop" ( 2826 ) void NetworkManager::SettingsPrivate::init() : New Connections list
NetworkManagerQt "plasma-desktop" ( 2826 ) void NetworkManager::SettingsPrivate::init() : "/org/freedesktop/NetworkManager/Settings/10"
NetworkManagerQt "plasma-desktop" ( 2826 ) void NetworkManager::SettingsPrivate::init() : "/org/freedesktop/NetworkManager/Settings/0"
NetworkManagerQt "plasma-desktop" ( 2826 ) void NetworkManager::SettingsPrivate::init() : "/org/freedesktop/NetworkManager/Settings/1"
NetworkManagerQt "plasma-desktop" ( 2826 ) void NetworkManager::SettingsPrivate::init() : "/org/freedesktop/NetworkManager/Settings/2"
NetworkManagerQt "plasma-desktop" ( 2826 ) void NetworkManager::SettingsPrivate::init() : "/org/freedesktop/NetworkManager/Settings/3"
NetworkManagerQt "plasma-desktop" ( 2826 ) void NetworkManager::SettingsPrivate::init() : "/org/freedesktop/NetworkManager/Settings/4"
NetworkManagerQt "plasma-desktop" ( 2826 ) void NetworkManager::SettingsPrivate::init() : "/org/freedesktop/NetworkManager/Settings/5"
NetworkManagerQt "plasma-desktop" ( 2826 ) void NetworkManager::SettingsPrivate::init() : "/org/freedesktop/NetworkManager/Settings/6"
NetworkManagerQt "plasma-desktop" ( 2826 ) void NetworkManager::SettingsPrivate::init() : "/org/freedesktop/NetworkManager/Settings/7"
NetworkManagerQt "plasma-desktop" ( 2826 ) void NetworkManager::SettingsPrivate::init() : "/org/freedesktop/NetworkManager/Settings/8"
NetworkManagerQt "plasma-desktop" ( 2826 ) void NetworkManager::SettingsPrivate::init() : "/org/freedesktop/NetworkManager/Settings/9"
NetworkManagerQt "plasma-desktop" ( 2826 ) void NetworkManager::SettingsPrivate::init() : New Connections list
NetworkManagerQt "plasma-desktop" ( 2826 ) void NetworkManager::NetworkManagerPrivate::init() : Active connections:
NetworkManagerQt "plasma-desktop" ( 2826 ) void NetworkManager::NetworkManagerPrivate::init() : "/org/freedesktop/NetworkManager/ActiveConnection/0"
NetworkManagerQt "plasma-desktop" ( 2826 ) void NetworkManager::NetworkManagerPrivate::init() : Device list
NetworkManagerQt "plasma-desktop" ( 2826 ) void NetworkManager::NetworkManagerPrivate::init() : "/org/freedesktop/NetworkManager/Devices/0"
NetworkManagerQt "plasma-desktop" ( 2826 ) void NetworkManager::NetworkManagerPrivate::init() : "/org/freedesktop/NetworkManager/Devices/1"
NetworkManagerQt "plasma-desktop" ( 2826 ) void NetworkManager::NetworkManagerPrivate::init() : "/org/freedesktop/NetworkManager/Devices/2"
NetworkManagerQt "kded" ( 2762 ) void NetworkManager::SettingsPrivate::init() : New Connections list
NetworkManagerQt "kded" ( 2762 ) void NetworkManager::SettingsPrivate::init() : "/org/freedesktop/NetworkManager/Settings/10"
NetworkManagerQt "kded" ( 2762 ) void NetworkManager::SettingsPrivate::init() : "/org/freedesktop/NetworkManager/Settings/0"
NetworkManagerQt "kded" ( 2762 ) void NetworkManager::SettingsPrivate::init() : "/org/freedesktop/NetworkManager/Settings/1"
NetworkManagerQt "kded" ( 2762 ) void NetworkManager::SettingsPrivate::init() : "/org/freedesktop/NetworkManager/Settings/2"
NetworkManagerQt "kded" ( 2762 ) void NetworkManager::SettingsPrivate::init() : "/org/freedesktop/NetworkManager/Settings/3"
NetworkManagerQt "kded" ( 2762 ) void NetworkManager::SettingsPrivate::init() : "/org/freedesktop/NetworkManager/Settings/4"
NetworkManagerQt "kded" ( 2762 ) void NetworkManager::SettingsPrivate::init() : "/org/freedesktop/NetworkManager/Settings/5"
NetworkManagerQt "kded" ( 2762 ) void NetworkManager::SettingsPrivate::init() : "/org/freedesktop/NetworkManager/Settings/6"
NetworkManagerQt "kded" ( 2762 ) void NetworkManager::SettingsPrivate::init() : "/org/freedesktop/NetworkManager/Settings/7"
NetworkManagerQt "kded" ( 2762 ) void NetworkManager::SettingsPrivate::init() : "/org/freedesktop/NetworkManager/Settings/8"
NetworkManagerQt "kded" ( 2762 ) void NetworkManager::SettingsPrivate::init() : "/org/freedesktop/NetworkManager/Settings/9"
NetworkManagerQt "kded" ( 2762 ) void NetworkManager::SettingsPrivate::init() : New Connections list
NetworkManagerQt "kded" ( 2762 ) void NetworkManager::NetworkManagerPrivate::init() : Active connections:
NetworkManagerQt "kded" ( 2762 ) void NetworkManager::NetworkManagerPrivate::init() : "/org/freedesktop/NetworkManager/ActiveConnection/0"
NetworkManagerQt "kded" ( 2762 ) void NetworkManager::NetworkManagerPrivate::init() : Device list
NetworkManagerQt "kded" ( 2762 ) void NetworkManager::NetworkManagerPrivate::init() : "/org/freedesktop/NetworkManager/Devices/0"
NetworkManagerQt "kded" ( 2762 ) void NetworkManager::NetworkManagerPrivate::init() : "/org/freedesktop/NetworkManager/Devices/1"
NetworkManagerQt "kded" ( 2762 ) void NetworkManager::NetworkManagerPrivate::init() : "/org/freedesktop/NetworkManager/Devices/2"
NetworkManagerQt "kded" ( 2762 ) NetworkManager::Device::Ptr NetworkManager::NetworkManagerPrivate::createNetworkInterface(const QString&) : libNetworkManagerQt: Can't create object of type 14 11 for "/org/freedesktop/NetworkManager/Devices/0"
NetworkManagerQt "plasma-desktop" ( 2826 ) NetworkManager::Device::Ptr NetworkManager::NetworkManagerPrivate::createNetworkInterface(const QString&) : libNetworkManagerQt: Can't create object of type 14 11 for "/org/freedesktop/NetworkManager/Devices/0"
file:///usr/lib64/kde4/imports/org/kde/plasma/components/Button.qml:194:5: QML Row: Possible anchor loop detected on fill.
file:///usr/lib64/kde4/imports/org/kde/plasma/components/Button.qml:194:5: QML Row: Possible anchor loop detected on fill.
file:///usr/share/kde4/apps/plasma/packages/org.kde.systemtray/contents/ui/IconsList.qml:53:9: QML MouseRedirectArea: Binding loop detected for property "width"
vmware-user: could not open /proc/fs/vmblock/dev
KGlobal::locale(): Warning your global KLocale is being recreated with a valid main component instead of a fake component, this usually means you tried to call i18n related functions before your main component was created. You should not do that since it most likely will not work
X Error: BadWindow (invalid Window parameter) 3
Major opcode: 2 (X_ChangeWindowAttributes)
Resource id: 0x3200082
X Error: BadWindow (invalid Window parameter) 3
Major opcode: 20 (X_GetProperty)
Resource id: 0x3200082
X Error: BadWindow (invalid Window parameter) 3
Major opcode: 20 (X_GetProperty)
Resource id: 0x3200082
X Error: BadWindow (invalid Window parameter) 3
Major opcode: 20 (X_GetProperty)
Resource id: 0x3200082
X Error: BadWindow (invalid Window parameter) 3
Major opcode: 20 (X_GetProperty)
Resource id: 0x3200082
X Error: BadWindow (invalid Window parameter) 3
Major opcode: 20 (X_GetProperty)
Resource id: 0x3200082
konqueror(2977) kdemain: Unknown class "" in session saved data!
konsole(2970) Konsole::Session::run: Attempted to re-run an already running session.
I/O warning : failed to load external entity "/home/vantonuccio/.qalculate/eurofxref-daily.xml"
I/O warning : failed to load external entity "/home/vantonuccio/.qalculate/eurofxref-daily.xml"
/usr/bin/skype: unrecognized option '-session'
Dropbox is already running!
New PolkitAgentListener 0xad2020
Adding new listener PolkitQt1::Agent::Listener(0xc073b0) for 0xad2020
plasma-desktop(2826)/plasma StatusNotifierItemSource::refreshCallback: DBusMenu disabled for this application
plasma-desktop(2826)/plasma StatusNotifierItemSource::refreshCallback: DBusMenu disabled for this application
QPainter::begin: Paint device returned engine == 0, type: 2
QPainter::end: Painter not active, aborted
Destroying listener
Removing listener PolkitQt1::Agent::Listener(0xc073b0)
kmix(2965) GUIProfile::~GUIProfile: Thou shalt not delete any GUI profile. This message is only OK, when quitting KMix
kmix(2965) GUIProfile::~GUIProfile: Thou shalt not delete any GUI profile. This message is only OK, when quitting KMix
kmix(2965) GUIProfile::~GUIProfile: Thou shalt not delete any GUI profile. This message is only OK, when quitting KMix
kmix(2965) GUIProfile::~GUIProfile: Thou shalt not delete any GUI profile. This message is only OK, when quitting KMix
No systemtrayicon available
No systemtrayicon available
startkde: Shutting down...
klauncher: Exiting on signal 1

Received signal:1->'Hangup'

Received signal:1->'Hangup'

Received signal:15->'Terminated'

Received signal:1->'Hangup'

Received signal:15->'Terminated'

Received signal:15->'Terminated'

OK


OK

startkde: Running shutdown scripts...
QThread: Destroyed while thread is still running
startkde: Done.
bluedevil-monolithic: Fatal IO error: client killed

I found the solution: the problem is specific to the way how the KDE send commands to the NVIDIA geForce GPU of my laptop.

After inspecting the ~/.tcshrc file, I noticed that I used a version which I migrated from a previous laptop, a lenovo Thinkpad e520. The present one is a Lenovo Ideapad s510p, with a NVIDIA GeForce GPU graphic unit: and here lies the problem. The old .tcshrc set the following environment variable:

setenv LIBGL_ALWAYS_INDIRECT 1

This activated "indirect rendering", which sends the commands to the X.org by GLX protocol, and then X send it to the GPU. For some reasons (unknown to me) this slows down terribly the communication with the GPU. If this variable is left undefined, KDE communicates directly with the GPU ("direct" rendering). I found this explanation at this link: http://unix.stackexchange.com/questi...-1-actually-do .