Thanks a lot for following up on this oldman. I actually restored the autorun file yesterday because I was just too anxious thinking I might have disabled recovery. So far Avast, Onescan, AVG, Spybot, and AVG Rootkit have NOT found an infection. I still sometimes get "System has recovered from a serious error" messages but I'm hopeful that is not malware-related. And I think the messages from AVG about changes to system files are OK. A couple of sites indicated the message just means the system files were updated at some time since they were originally installed, not necessarily since the last scan.
Re the "serious error" message I did check out your reference but I didn't find files of the type the article discussed (.sys files with hidden attributes, odd names, and no product, version, or company info).
I will keep you posted. Thanks again!