randomly distorted display

[Dirk Reiss <d.reiss@tu-bs.de>]

Hello,

on my Dell Inspiron 5150 i randomly (i.e., sometimes several times a day, 
sometimes not at all for several days) experience problems with a completely 
distorted display. It looks like some kind of small symmetric blinds all over 
the screen (under X) and on the tty consoles there are some will blinking, 
colored ascii characters. 

Actually, i use kernel-image 2.6.9, inside there is an ATI Radeon 9000.

Any ideas what this could be? Or in general: what could cause this?

Many thanks in advance for any suggestion.

Cheers,
Dirk