try pulling the car out of the slot... is it a pci card or a AGP??? more then likeyly AGP....
pull out the car, if you have a can of air, give it a quick spray, might just be a dirty slot...
if you have already updated all the drivers you should be ok their.
if you have another PC to try it in do that, if the problem persists, then its the card, if the problem goes away, then you have a faulty MB...
good luck!