I really don't know what to say, never seen that with a working card.
Could be the card went bad, I would try another video card to see.
If you card has a cooling fan make sure it is still connected and running.
Make sure memory is inserted all the way in and tight.
Could be a software glitch of some kind.
You could try booting to the command prompt.
type scanreg /restore and restore a registry from a previous date before the problem happened. Note any software, etc, that has been installed since the registry date will have to be reinstalled.
If that doesn't work I don't know