Service.exe trying to terminate pdengine.exe

This has happened twice in the last couple of days. Both times the cable to the modem was unplugged (we have been having thunderstorms in the area) when the computer was started up. I've run checks with Spybot R+D, Adaware Counterspy, AVG and Hijack This. I can't find anything strange. Why would Services.exe try this? I saw a thread suggesting that Services.exe be added to my list of protected applications which it isn't on. But presumably if it has been nobbled in some way I wouldn't want it protected?

Locations of programs:
c:\windows\system32\services.exe)
c:\program files\raxco\perfectdisk\pdengine.exe

Hoping someone can help.

Thanks

Chris (Hunt)