screen flashes black after windows update

Hi there,
Due to all the warnings of a major internet attack, I
followed the advice given to me from Microsoft's home
page "Action for Windows users: Read Security Bulletin
MS03-026, and install the security patch immediately".
After doing this, my screen is now periodically going
black for a second before returning to normal. It
happens roughly 2 or 3 times within a 5 minute period.
This is extremely frustrating. I assume that it has
something to do with the NVIDIA media center that it
installed which I did not have on there before the
update. I tried uninstalling that. Then I went to the
device manager and right clicked on the GEforce 2mx/mx400
and told it to update. It looks like it just reinstalled
the same thing. Screen is still going black. I'm not
even sure that it was the video update that caused this
new problem. Please help asap. I have a web design
business and I'm afraid my monitor or computer is going
to explode if I don't get this fixed asap. The video card
is only a few months old and it has 64 MGS RAM.