KDE Screensaver (any) worked fine for a week, but now won't auto start. Can't find solution in KDE Help. Would appreciate suggested fix.

what version of KDE?

did it work until you did an upgrade?

in screensaver settings does it work using the test function?

rename ~/.kde/share/config/kscreensaverrc and try again

try as a different user

KDE 4.4.2
Am using Ubuntu 10.4 - installed kubuntu-desktop & associated files with Synaptic.
Screensavers set to auto run, all work with test function.
current ~/.kde/share/config/kscreensaverrc
[ScreenSaver]
ActionBottomLeft=0
ActionBottomRight=0
ActionTopLeft=0
ActionTopRight=0
PlasmaEnabled=false
Priority=0
Saver=koceansaver.desktop
Timeout=60
Did not do an update.
rename ~/.kde/share/config/kscreensaverrc to what?
Will setup a new user & try that.

rename ~/.kde/share/config/kscreensaverrc to ~/.kde/share/config/kscreensaverrc-old doesn't actually matter as we're just trying to get KDE to revert to the defaults and we're renaming it so you have a copy if need be

Bumpalot - that's a pretty old version of KDE (current is 4. might you consider up'ing, though in Ubuntu world you'd probably need to up to Oneiric to get a new version of KDE and probably add the backports repo

Thaanks! renaming worked - screensaver is now activating.
According to KPackageKit, The only version shown of Kubuntu Plasma Desktop system is 1.174.1(amd64)
which is the one I installed. Should I be installing something else??

sorry no idea what "Kubuntu Plasma Desktop system is 1.174.1" is, it should have a numbering like 4.4.5-0. I'm just mentioning that what you are running, KDE wise, is a bit old and since 4.5 there have been enhancements and bug fixes - but if you are comfortable and happy and receiving security updates ........

Since my last post have totally reinstalled Ubuntu Lucid, then installed the official package kubuntu-desktop.
Am still unable to get ANY screen savers to auto start (any category). The desktop is working fine.
The only file I can find is ~/.kde/share/config/kscreensaverrc
Contents:
[ScreenSaver]
ActionBottomLeft=0
ActionBottomRight=0
ActionTopLeft=0
ActionTopRight=0
AutoStart=1
Lock=false
PlasmaEnabled=true
Priority=0
Saver=koceansaver.desktop
Timeout=60
Is there another file such as xsomething that could be edited?
Am using nvidia-settings: version 295.53 (buildd@litembilla) Wed May 16 19:23:51 UTC 2012, Twinview which works fine.
Composting OpenGL) is active - Direct rendering enabled, use VSync if that info has any relevance.

I notice the line "PlasmaEnabled=true" in there. Is "Allow widgets on screen saver" checked? If it is, try unchecking it.