The PC I am working on has had significant virus infestation but this has now been fully eradicated by the use of various tools around the internet. Now, having established a fully working, virus-free system I have the problem that there are no devices in Device Manager and the Plug Play service isn't started and can't be started. The message is "The Plug and Play service on Local Computer started and then stopped". This problem has occurred during the disinfect process because I have proved that the service was operating a couple of days ago. I did this by temporarily restoring a copy of the registry files and all was fine.
Since the registry copy a couple of days ago, various anti-virus, malware scans have been run and one of these may have done something to the registry which prevents Plug Play starting. Thinking that some system files were corrupted at some point by the virus infestation, I have upgraded to XP SP3 hoping that the offender would be updated but this makes no difference, which it probably wouldn't if the resgistry was the problem.
I have tried every fix attempt recommended on this topic including checking for '$%&'()' corruptions in the registry, checking Plug Play startup and path, SFC /scannow, AproposFix.exe all to no avail.
Would really appreciate some further ideas. As I said earlier, I'm convinced the registry is somehow at fault, but what should I try?