HI ! i have the exact same problem with my 6870.
but its from asus.
I think on the first time i used this card few years ago , it hapend the same, not sure but think bios date was crazy to the future.
Well, i dont have pantience now to try it , but probaly it will, (changing date of bios ), cause this *****s program it to do this.
It also hapen to me in the last weeks.
anyway i'l try loo find some hackers that release some bios update!
zepiwane , did you find any soluction by now ?