The other minute I updated Ubuntu from 10.10 to 11.04. I configured the system to always log in user A.
Now when I start it, the computer boots and loads the Desktop of user A, but there you can do nothing but moving the mouse. The Unity panel is empty and the task bar is not clickable, as well as any items on the desktop.
Switching to a terminal with Ctrl-Alt-F2 I found out, that the Zeitgeist daemon hangs and became a zombie, which I think might be the reason. However, if I kill the daemon, the desktop becomes fully black.
I moved old config files from /home/userA away (.compiz, .config, .local, .gconf*, .gnome2*), but that had no effect.
Has anyone an idea, what I could try? My only idea left is to re-setup the whole system (not my favourite).
Update: It's something stranger. After
aptitude remove unity zeitgeist-core the computer loads Gnome, but with a similar issue: Only the Desktop background and the mouse are visible. No panels, no desktop icons, no nothing.
Journey continues: I disabled autologin via terminal. The login screen appears on startup as usual, and I can select any normal user. But for each one the result is the same: No interaction with desktop possible.
Next puzzle piece: This thread suggests the nVidia driver being the culprit. The suggested solution ("Load clasic, no effects") works for me. Issue solved, but I'm not satisfied.