You may have to uninstall the existing drivers before you can successfully update to new ones.
ATI/AMD has instruction videos on how to install, update, and uninstall drivers at the bottom of this pagehttp://support.amd.com/us/gpudownload/Pages/index.aspx
The video instructions are for Windows 7.
I don't know if you're using Windows 7 or XP.
If you're using 64-bit Windows 7, be sure you get drivers for the 64-bit version of Windows 7.
If you're using the 32-bit Windows 7, you'll want the drivers for the 32-bit Windows 7.
If you get drivers for the wrong version of Windows, it could cause error messages or the drivers might not even install.
If you ONLY see the error message after trying to run the game, the problem may be an incompatibility between that particular version of the drivers and the game -- or it could be due to a conflict the drivers are having with previous drivers that weren't uninstalled before uninstalling the new ones.