Very annoying, very strange C&C Generals Zero Hour Error

HI.
I've got a really annoying error when I go to run C&C Zero Hour,
It started when I replaced my R9600xt with A Nv6600gt,
Ever since then, when I go to run ZH after the second splash screen
it pops up with an error saying:
Plese make sure you have DX 8.1 or higher installed.
Also verify that you video card meets the minimum requirements.

The stranger thing is that normal generals still works fine, no error.

I've reinstalled the expansion and generals multiple times, restarted the machine, tried to reinstall DX, but its all gotten the same respons.

I'm running windows xp sp2, amd 2600xp, leadtek a6600gt agp force ware 84.21 driver, 1024MB of ram, 120GB sata HD, 160GB sata HD, asus A7N8X-E nforce 2 chip set with nforce 5.10 driver.

Any help would be most apriciated, and might save me from going insane trying to solve this problem.
Any sugestions welcome.

Yep; That's most likely the problem...

try to uninstall the video card. then reboot the computer.

When Windows will start it will say that it has a unknown hardware and will install the generic driver ( which sucks)

go on Nvidia.com and download the lates driver for your card ( not the one from the CD of that came with your card)

install those driver and reboot the computer.

now see if Zero hour works correctly.

if it doens't, you can also try to remove directX. Reboot and then download DirectX 9C from Microsoft website and install it.

( the reboot are simply to make sure windows doesn't have anything in his memory that could corrupt your installations )