Noir I am running XPSP3. That may be a difference.
If you do have catalyst/ATI control center I suggest you do this.
Go to Settings/Control Panel/Display/Settings/Advanced. this should activate Control Center.
A drop down menu appears ....I'm using crossfired ATI 4850s.
the screen on the right should show a graphic of an auto driving on a road.
Underneath that graphic might be a slider or something that says Standard...(could be a slider or a chk box)
If you scroll down the menu on the left you will see the settings that you can adjust.
The last one in the Menu should be Crossfire. When you select Crossfire you will see text that explains
that MAKE SURE when running Crosssfire you are in standard mode.
If you didn't find it at the first screen I described above click on the selections in the drop down menu
to the left. You will find it.
Hope this helps
Hajo