What has happened?????

Hi all, I have a PC running XP professional that suffered some sort of attack recently – every shortcut was changed to an .lnk file, and most shortcuts would only open with Notepad. On botting there was a huge flurry of registry changes intecepted by Microsoft’s Spyuware Remover Beta, and I turned the machine off to try and avoid a suspected glitch in the system. I placed the affected drive into another PC and performed a Spyware and Virus scan (using Adware pro 1.06 and Symantec’s Norton Antivirus 2005 (with ALL updates applied) to no avail – nothing was found.
I had a WIndows 2K Pro machine similarly affected some months ago….has anyone else come across this problem?