Comment 38 for bug 152648

i have this bug too. just started to happen today.
i am on 7.04 i386 desktop (running on a file server). the server is headless, so i log in via vnc on screen :1.
since today, when i log in to the desktop using vnc, then close the vnc session, the next time i log in, i am not getting back to the desktop where i left it, but to the login screen again. when i close the vnc session, it crashes X and restarts it, with the above error message.
therefore i doubt it's a nvidia driver issue.
yesterday i installed webmin, but it's unlikely to have anything to do with this.

the other thing i did yesteday was, i found xubuntu-system-tools in the synaptic package manager (i'm using xfce) and installed it, which caused the removal of gnome-system-tools and ubuntu-desktop packages. and in system logs, the x crash error message always appear before the line "gconf is not in use, shutting down".
so i believe, the crash is caused by yesterdays auto-removal of gnome-system-tools.
i check this out now, will reinstall gnome-system-tools