Koran, it's a know problem with all Radeon's (especially the 9700Pro) will do that.
I had EXACTLY the same problem you did. I ended up replacing the card to solve the problem. My GPU fried because it got too hot. The stock ATI fan didn't cool the GPU enough which eventually damaged it.
Try taking off the stock fan on the video and put on a big a$$ one.
Also, try installing Omega's drivers from
http://www.omegacorner.com.
You've elimated a lot of the common issues by the looks of it. Make sure your chipset drivers are fully updated too.
Finally, turn down the AGP multiplier to 4X and turn off Fast Writes then run the test again.