I'm using Ubuntu 13.10 and every time I try to start Mathematica, my Ubuntu session just crashes and I get thrown to the login screen. This also happens if I try to run Mathematica from another computer through SSH and on both Mathematica 8.0 and 9.0. This behaviour started after the last time I did the normal software update for my system.
How can I try to solve this problem? I find nothing in the ~/.xsession-errors errorlog for X.