I've had this problem after like the first three times the computer starts up (after install ubuntu). Ubuntu boots up like normal, I login, then after a login I am presented with about a dozen error messages reporting that it was not able to load certain applets. because of this I cannot see the clock, the task bar, and others.
Another problem I'm experiencing is that certain programs don't work at all. For example if I try opening a text file it would appear to be opening gedit (the default document program) but then nothing happens. Even some setting don't work (power management, etc).
The only thing that I did since installing ubuntu, is install the basic c++ development libraries, which came on the ubuntu CD.
If anyone can help me with this problem I would appreciate it.
It sounds like something helpful modified your environment files, and you do not have the right $PATH, $LD_LIBRARY_PATH, probably within:
/etc/profile, /etc/bash.bashrc, ~/.bash_profile, ~/.bashrc, ~/.profile, ~/.kshrc
you might also try to re-install the gnome desktop:
sudo apt-get update && sudo apt-get install ubuntu-desktop
Yes, X resources and java properties can get corrupted and mess up this way, too.
I lost my SQuirreL the other day on Windows XP Pro because the JDK install did not update the directories reflected in the system's JAVA environment variables, and I had just removed old JDKs with old JREs. There are many ways to destabilize an install!