This customer had a PC running Windows XP, a core2 duo CPU, a high-end ATI video card, and 2 Gb RAM.

But he cannot run World of Warcraft (which is what the PC is mainly used for). It did run WoW for a few years, but after moving house, it seemed to stop working.

Whenever WoW is run, is gives the error message: Failed to find suitable display device.

After a bit of research, it seems that the prevailing wisdom on the net is that the ATI driver and Catalyst Control Center need to be re-installed.

So I try the standard add/remove; download the latest driver from the ATI website, and install the latest ATI driver and CCC.

But WOW will still give the same error after the latest driver is installed.

I make sure I have the latest version of DirectX… but the problem persists.

The next step is to uninstall the ATI software again, but this time make sure all ATI files are removed from the system (including program files, windowssystem32drivers, etc) and remove all ATI entries from the registry.

Reboot, make sure XP is using its generic video drivers, then re-install ATI drivers and CCC.

But the WoW problem is still there!

I run some intensive stress-tests of the CPU, RAM, and video card, but find no problem with the hardware.

A virus/spyware scan finds nothing wrong with the PC.

In the end, the only options is either a mammoth re-install of WoW, or a slightly more mammoth fresh install of Windows XP, and then an install of WoW.

Due to time constraints, the customer decides to reinstall XP and WoW himself… after which, the PC works normally again.

Looks like this is one of those rare situations where a re-format and re-install is the only solution.