Scrambled / distorted screen elements.

[strrrts]

It happens to every element on the screen, icons, shapes or text (except for backgrounds) and is a progression, first some text then icons then window edges. It looks like this : http://i.imgur.com/M2l2Ad9.jpg (this is just the text phase getting bad)

Any suggestions?


There are no symptoms for the first couple hours but once it shows it just get worse and worse unless I reboot the system.