Yea I've been having this problem since I downloaded the update (XP) for video GeForce 8600 GT, it doesnt happen during the day just at night a few times (2 or 3) basically everynight now.

It's only when I'm playing games that it occurs. The screen is filled with very thin dotted vertical black/transparent lines, and the colours are a bit discoloured (it's hard to explain) usually it will disappear after a few seconds but most of the time i have to hit the windows button to get back to the desktop and it will be gone.

 

I've never had it crash or freeze and i can still play but it get's annoying and I don't see why it should be happening.

 

Dell just told me to download it again, i did, still happening!

 

I only brought my laptop in october last year and had no troubles, except for now.

 

Help would really be appreciated :)