startx does the same, just hangs
hmmm, probably a wonk /etc/X11/xorg.conf file.
Id:
$ sudo apt-get install nano
$ sudo nano /etc/X11/xorg.conf
and have a look at the vid card section.
you can alternately:
$ sudo dpkg-reconfigure xserver-xorg
You might have to reinstall any special drivers for 3D acceleration, but it doesnt sound like your install is hosed.
You can also install the latest snapshot:
$ sudo apt-get update
$ sudo apt-get dist-upgrade