X crashes after upgrade

[kolesarm]

I've just upgraded to Intrepid (Kubuntu), and for some odd reason, X decides to kill itself every half hour or so, for no apparent reason. I am just editing text, have firefox and amarok running, when I suddenly end up at the login screen, as if I pressed ctrl+alt+backspace, which I haven't.

Anyone has any ideas about why this might be?

I really is annoying.