Over time, video drivers can become corrupt and require reinstallation.
Reinstallation is the simplest course of action to take. The next thing to
do is upgrade your motherboard chipset drivers.

Since you have not posted any specs about your PC, it's virtually impossible
to offer additional advice.

Joe

"John" wrote in message
...
Like I say, this has happened to me before and was found
not to be a problem with the video card, but the monitor
(which seems to be ok this time around).

I have not just re-installed Windows, this is something
that has happened between closing down the computer and
starting it up again, which is baffling.

Thanks