Thanks for your help. However I have not been able to solve the problem. For those who don’t know, the Avast Uninstall Utility will run from a BootCD, but will not remove anything from the registry of the OS installed on the HDD. Only the files in the Avast directory will be removed.

Now I will check some more for root kits or other malicious code before I reinstall Windows 7 to have the computer back in action.