My Xubuntu 10.04 system logs me out seemingly at random. How can I diagnose why this is happening and correct it?
there were some bugs in 10.04 related to the X-server. occasionally, some processes would try to render objects in such a way as to cause X to crash. GDM will notice this, and restart X, presenting the login screen again.
Fix is to generate an xorg.conf file, and then update that file to use a different acceleration method.
Press CTRL+ALT+F1 to access the first virtual console, and login. Once you're there, you'll stop gdm, generate the xorg.conf file, and restart gdm.
Now that the xorg.conf file exists, make two small changes to set the following options:
Without knowing what kind of hardware you are using, you may have to fiddle around with the AccelMethod setting. If you have intel hardware, you could try setting it to "UXA". You can also try "EXA". Check your default.