Glitchy Lock Screen

view story

http://forums.fedoraforum.org – I am currently Using Fedora 18. When I lock the screen with GNOME Shell it locks but when I leave it locked for over five minutes when I go to unlock it it the screen repeatedly flashes itself at me. Highly annoying. Another problem is I used to take this computer to school and the students always stared at it like his computer is broken or his computer is having a seizure. And it's not just with gnome. I see this happening with KDE XFCE LXDE MATE and Cinnamon. Does anyone else have this problem with Fedora 18? Is there a work around? (HowTos)