have you swapped out the monitor? almost sounds like the monitor might be going away on you when graphics modes switch. you sound like you have tried a different video card but what about the monitor itself?
I would also check the video cable. Perhaps a loose pin?
TomG wrote:
have you swapped out the monitor? almost sounds like the monitor might be going away on you when graphics modes switch. you sound like you have tried a different video card but what about the monitor itself?