Did you have this issue before you upgraded and what did you upgrade from?
If you upgraded from a Nvidia card then you will have to run driversweeper to get rid of all the Nvidia junk left behind when the drivers been uninstalled. That may cause a few errors.
If he did go from Nvidia to ATI/AMD, it's very important that he leave the Nvidia PhysX drivers installed. If they are remove, any games using a PhysX engine will not work and give an error, which could be his current problem.