removing graphic adapters (both built in and discrete) drivers in Safe mode didn't help. I resorted to system restore instead then things were back to normal again.

thanks anyway.

Marin85,

Opsss... i got what you mean, I've just changed the settings on youtube.

The screen starts to flicker even before the login icons appear on screen. Though i can see the login screen just fine in Safe Mode. I'm thinking my Vista might've been corrupted somehow...

Out of the sudden, my W500 with Vista Ultimate 32 boots up with screen flickering nonstop http://www.youtube.com/watch?v=dTucGPj9f7M . Boot in VGA mode won't work either, but screen seems to be okay in Safe Mode only. Managed to boot via Last known good configuration once and it worked fine for that...