Description of problem:

After a period of time, the mouse focus changes on my desktop such that there is clearly a gnome-screensaver running but not actually displaying anything (occasionally there is a blue rectangle in the top left screen corner). Since there is no dialog displayed (or anything else other than my regular desktop) I cannot enter a password or cause the screensaver to exit. The only recourse is to switch to another tty and kill the gnome-screensaver.