Monitor goes black

Hi I have a Dell 1800FP LCD monitor.I bought it from a
second party so no support from DELL. My monitor will go
black at random.When i turn the monitors power off then
on again the picture comes back on. The monitor worked
fine for 5 months now it does it alot. Especially when
playing games. The problem started when I had Windows ME
on my machine. Here are the steps i have taken to correct
the problem. I upgraded to XP pro put in a new ATI 9800
Pro(needed one anyaways) and the monitor still does it. I
even tried it on my wifes machine which has XP pro on it
and it still does it. I uninstalled it in device manager
then reinstalled.I have reset the monitor and did a self
test on it and it checks out ok.But I go to use it again
and the same crap. Im hoping it might be a bad driver.
Any help would be great. My processor is an AMD 2500xp i
have 512mb DDR ram and running xp pro.