I had this same problem on my old machine (ASUS P3V4X - VIA chipset). I also tried everything I could think of without being able to solve the problem. I thought it was the graphics card at first, but now it's in my new machine (ASUS A7V333 - VIA chipset) the problem has gone away.
I use the same OS as before (Win2K), the same DX8.1, same Detonators (30.30), same 4in1 VIA drivers (4.40) etc etc as my old machine, just don't get the same problem.
From this, I guess I'm saying it could be the motherboard, or the VIA chipset on it (my new mobo is a different VIA chipset).
I guess it could also be because my new machine was build from separates and I have installed all software onto a clean machine.
Hope you get this sorted, because it is VERY annoying. I'm lucky in that it doesn't do it any more now I have a new machine.
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