I've installed Ubuntu 10.04 (64bit) as a guest OS in VirtualBox, using Windows7 Professional (64bit) as host.

After Ubuntu install, I did installed Xfce4 (sudo apt-get install xfce4). Logged in using a Xfce session, and when I logged out, I couldn't see the login box anymore, only the regular gnome background from login screen.

Then I restarted the virtual machine, and now I'm not able to see the login box anymore, only the gnome background.

Does someone knows how to solve this?

Thanks in advance

Update: I've tried to use Xubuntu, that comes with Xfce. And I'm facing the same problem. As a common denominator from the two cases, now I see the problem arises after I've updated the system, and then installed curl (via apt-get), zlib (make process), git (make process). But I'm not sure this can be the cause for this ...

Update: I isolated the problem. The bad guy is zlib, but I don't have a clue why. In fact, it does crash not only ubuntu and xubuntu, but also Debian (Yes, I've tested all). I'll keep this question in case someone have the same problem, but I think my initial question is not valid anymore.