Screensaver locking system

I think there must be some issue with the video drivers because I was going through the list of screensavers to see what they looked like and when I got the the Ant* screensavers (Antinspect, AntMaze, and AntSpotlight), it wouldn’t show a preview. I was able to switch from Antinspect to AntMaze, but then the Screensaver Preferences window stopped responding and nothing I did would let me get out of it. I was also unable to switch to any other application.

Is there a terminal command which lets me reset the Screensaver Preferences back to the default? Is there another which lets me remove specific screensavers from the list of screensaver themes?

I’m using Gnome 2.28.0 in OpenSUSE 11.2