Originally Posted by JemyM
Very odd indeed. Do you have another graphic card in your system? Perhaps an on-board gfx chip? Or maybe you had an ATI driver installed previously which didn't deactivate itself properly?
The check nHancer is does is actually very simple. It asks Windows about "primary display" and which driver is responsible for it. If the driver is not called "nv4_disp", the message you got is shown.
If you ever happen to get this problem again, I'd really be interested in learning what driver you go instead of "nv4_disp". Tools like Everest should report that or I create a small program which does just that.