I am running Ubuntu 12.10 on a Dell Dimension 3000 desktop computer. I removed all partitions from the hard drive before installation, installation was flawless, but when I log in, I only see the desktop background and the normal pointing cursor (does not indicate loading, etc.). The first time I noticed this, a few error messages would appear saying that some program had closed unexpectedly (the first one said compiz had closed and asked if I would like to keep it remain closed or relaunch). After pressing the console power button one time, it prompted me to shut down, log out, or hibernate, etc. After restarting, it does the same thing, although I do not see any error messages.
I have been able to boot Lubuntu's LXDE on the same computer in the past, so a roadblock of this error was not entirely anticipated.