Man, if they couldn't answer your question at Rage3d (and they have a lot of "qualified" gurus there!) don't expect much from HWC. No offence, guys.
The only thing I've ever come across with my 8500 which is even remotely similar is when I'm overclocking using Rage3D Tweak. If the registry is set up to change the clockspeed of the 8500 (I'm currently running 310/310MHz) and the "Enable 8500/7500 Ocing" isn't checked in Rage3D Tweak, then the entire screen displays vertical orange/purple lines and the machine appears to lock up. It's pretty easy to fix though... I just boot in safe mode and enable OCing as mentioned before.
More # please...
Bink's HWC GALLERY
Opteron email@example.comGHz (stock HS/fan), Asus A8N-SLI SE (passive NB), 1.5GB RAM (2:3:2:5, 2T), WD Raptor 740GD 74GB, Maxtor DM10 300GB, Asus EN7600GT SILENT@???, M-Audio Revo 7.1, Nebula DigiTV, Dell 2005FPW, Enermax 431W Active.