Oh that wonderful ATI Radeon software!
Problem after driver update which updated the Radeon Adrenalin software (which wants to do Everything for All my games but can't find URU with both hands)
Problem as described. Uninstalled Adrenalin using Revo Uinstall and there were heaps and mounds of entries in the registry. Problem remained but Revo came back to say it wasn't finished when I rebooted. It pulled off two more handfuls of registry and problem gone. A registry cleaner then found another 300 leftovers.