I've just put a clean install of XP pro on my PC and installed the latest catalyst drivers (5.11) for my Radeon 9800 Pro. When I run the DirectX diagnostics and go to the display tab the button that should allow me to enable AGP texture acceleration is greyed out and disabled. I know for a fact that it should be enabled because it has been enabled before! I've looked all over the web and tried all the recommended solutions I can find - I've updated my mobo drivers using MSI live update (I have an MSI KT4 Ultra mobo - MS-6950), reinstalled the catalysts, reinstalled DirectX, but nothing seems to work. Can anyone suggest something I'm missing ? I know what I'm doing when it comes to PCs, I work with them for a living, but this has got me pulling my hair out.

hmmm... weird... I suppose you have windows SP2 and the last directx righT?? There may be an option turned off in your mobo configuration. You said you just made a clean install in your pc.. depending on how deep that was your bios configuration may have changed... for example the agp slot may be running at 4x instead of 8x and that may be disabling texture acceleration. I recommend that you check the bios in case your computer it's "missing something" about your video card. Also check if it's well pluged in.

AGP 4x or 8X will not disable the texture. Check in the bios and see whether the AGP aperture size is set to 64 or 128Mb. If it's there then it should be the driver (get a lower version and try). You can double check by first uninstalling the catalyst driver, bootup with xp driver, run dxdiag and check whether the texture is enable, then re-install lower version catalyst driver.

Thanks for the replies, I managed to fix it last night. I'd used the MSI Live Update program to update all the relevant drivers for the mobo, but as this didn't solve the problem I tried the VIA 4in1 drivers directly from the VIA site. After installing version 4.56 (I think ! can't remember exactly) and reinstalling the Catalysts the texture acceleration is now enabled. Dunno why I didn't think of that before.....