I had a challenge with an Nvidia API conflict after installing VMware Player tools. After doing some research, I found http://askubuntu.com/questions/145195/nvidia-driver-problem-after-updating-to-12-04, resolved the issue by purging the driver installed by VMware and installing a new one from the command line. The gui is back but it is not functioning correctly. These are the symptoms:

• After entering my password, the 4/5 icons of a hard disk, spanner and wrench settings logo, globe and Desktop come up. The KDE logo does not.
• Normally I have 4 desktops. Now I am down to one. If I try to increase the number beyond 1 through Pager settings, the application of the settings is ignored.
• Any software I open is static in one place and stack at 0,0. Sizes of the windows as last used is intact but all positioning starts at those coordinates.
• Borders and what not for resizing, moving, minimising or other manipulation of a program window don't exist.
• All closing of programs has to be done clicking Quit through the menu. Keyboard shortcut of Ctrl+Q will not work and the X button top right does not appear.
• Whereas I can enter my password with no challenge on start-up, using the keyboard is intermittent. Editors like Kate or Kwrite will take data. But if I start a software that requires root permissions, the dialog box for the password will not accept input.
• Any software I launch the tab for the program does not appear in the task bar.

I do have a backup but it only covers /etc/, /home/, /usr/ and /var/ plus their subdirectories respectively.

Is there a re-install I can deploy to fix this? Any help someone can offer for a solution will be greatly appreciated.

The Windowmanager (KWin) constantly crashes and so may/will other applications because Canonical/Ubuntu out of all distros is completely incapable of managing driver installations what means you now got a mixed mode installation of the nvidia blob and the mesa drivers and load the wrong X11 driver for the loaded kernel modules and linked libGL.

And by blindly following this 2 year old instructions, you've now completely screwed your system...

The first step will be to investigate the present system. Install "openbox" (a slick WM that does not link OpenGL and will allow you to interact with the system in a half-wise way - you should be asked whether to start it if kwin cannot be started/constantly crashes)

Then please post/attach the output/content of
- /var/log/Xorg.0.log
- "lspci" # (<- use xterm or VT1 if konsole crashes as well)
- "ls -l /usr/lib/libGL*" # (<- idem)

Rather than deal with an individual like you, lubeking, I am solving this on my own. I bid you peace and goodwill on this festive season

If you want to use the nvidia driver, ensure it shows up in Xorg.0.log and that /usr/lib/libGL.so and /usr/lib/libGL.so.1 link sth. like libGL.so.315.12, where "315.12" is the version of the installed nvidia driver.

We've had dozens of bug reports for random crashes because of broken binary driver updates on ubuntu, so you're not alone on this and googling for more recent dates will get you better information on the topic.
If you want to take a good advice and in case you followed the help and installed the nvidia driver by hand: uninstall that installation first and start on a package clean system.

In case you feel like you need assistance: don't hesitate to ask, for even though i may sound annoyed by this issue, the target is Ubuntu for not getting their package deps in shape over months - certainly not you.