After upgrade xscreensaver to version 4.23, screen starts blinking (using Gnome 2.10.2). If I unmerge xscreensaver, problem was solved.
What video card do you have?
(In reply to comment #1) > What video card do you have? > I have a PCChips M863G motherboard, with embedded Real256E 3D Graphics.
*** This bug has been marked as a duplicate of 113951 ***