Comment 14 for bug 342980

i still have this problem (with the latest updates and such). it seems to happen when the screensaver runs (although not necessarily every time, and not necessarily in a given amount of time -- sometimes, it happens within a few minutes, and other times, i can leave the screensaver for hours to have found that it died only a few minutes before i came back).

i have an nvidia card and am using compiz as well. killall gnome-panel fixes the problem temporarily until it decides to repeat itself again.