Garbled Screen Problems

[-Z-]

Hello All,
I have been having some intermittent problems with my computer's graphics. Every now and again (becoming more frequent), the computer screen freezes for a moment, and then overlays purple or green blocks in a diagonal pattern across the screen, or comes up black and reads "No Signal". The cursor and screen then freeze. In each instance, I am unable to log out properly and have to hard boot the machine. The problem often remains following the reboot, unless I wait about 5-10 minutes. The problem is someitmes preceded by colored shadows behind the cursor.
The problem usually occurs during normal use of the computer, such as office applications or running Internet Explorer. I don't run any graphics-intense programs on this machine.
I am using an ATI Radeon 9700 Pro Video Card with the most recent driver installed. I have tried rolling back the drivers several steps, with no luck. My AGP setting is 4x with Fast Writes off. My monitor is brand new, and I have had the same issue with the previous monitor, so I have discarded that as being the problem, and I suspect that my video card may be failing.
Does anyone have any suggestions on how to either remedy or troubleshoot this problem? I don't want to go and replace the video card and find out that the problem is still there (my wife is still a little mad about the new monitor).

Any help or suggestions are greatly appreciated. If you need any further elaboration on the problem, just let me know (its a little difficult to describe).

Thanks!

[TripleRLtd]

I am using an ATI Radeon 9700 Pro Video Card with the most recent driver installed. I have tried rolling back the drivers several steps, with no luck.
My AGP setting is 4x with Fast Writes off. My monitor is brand new, and I have had the same issue with the previous monitor, so I have discarded that as being the problem, and I suspect that my video card may be failing.
Does anyone have any suggestions on how to either remedy or troubleshoot this problem? Good description of the problem there. And, it sounds like the video card is the problem. The GPU (Graphics Processing Unti) has ram/memory on it, too. And, quite often, that is the source of video problems, too.
You can try this: change the display to Standard VGA and run it like that for a day and see if it does the same thing. What we need to eliminate as the source of the problem is the card itself or the drivers.
Also, see if you can borrow or use a good working video card for a bit, just to be sure. Also, try pulingl out the video card and use a pencil eraser to clean the contact surface and then reinstall it, making sure you push it down all the way.
And, just so you know: it is NOT your monitor.

[-Z-]

Appreciate the quick reply:
Can you tell me off hand how to go about changing the settings to Standard VGA? I'm running Windows XP with the ATI Catalyst Control panel if that helps.

Again, thanks for the quick response!