Yep...you just have to uninstall the 1960s Groove mod...
This is definatly a problem with EQ2 and your 8500gt.
EQ2 is a demanding game and as Triscuit said, this looks very much like over heating or overwork for the card.
Using ProfitUI instead of the default UI will increase the demand on the graphics card, but it is not the cause of this.
I would suggest that you double triple check you are using the most up to date drivers and keep on checking for updates as there may be one that fixes this. And also check the official Sony EQ2 forums to see if ohers have this problem.