Hi Pr,
No, you don't want to flash that card. I just asked in case it had been a flashed card that maybe that was a part of the trouble. Most flashed cards work fine, but some can be buggy.
Hmm,... what kind of monitor do you have? When did the problems start? Did they begin after an upgrade or anything? Is that Mac also running 10.5.7?
One thing I would try, and there are documents saying how, would be to remove the card, blow out any dust in the slot and surrounding area, and reinsert the card.
I know with 10.5.5 that more than a few people had display problems, mostly with the x1900 as I recall. So it might be a software related problem with yours as well. I'll do some searching around and see what I can find.
One good test though would be to put another card in it and see if it still happens. Any other Macs at work you could swap cards with as a test?
Edit: Qm's link below is unsettling. Maybe that's the problem right there.
Message was edited by: Samsara