Hi, I have just installed an AMD Radeon Sapphire HD 7870 graphics card & Crysis Warhead will not run as I get a message "AMD RADEON HD 7800 series" [Vendor = 0 x1002, device =0 6818]

The drivers are up to date for the GC & Windows7.

When the box appears if click OK the box disappears & the game will not start.

What could be causing the issue?