Windows XP password has been added

I have a computer shop...I had 4 computers to enter my shop in the last week with the same problem. XP has added a password to the administrator's account. I cannot access the computers via safe mode or anything. I also have a program to reset the password but it say's there is no password to change. Has anyone else had this problem? Two of the customers say it started when they restarted after a Windows update. These customers are known to keep Norton's up to date also. I have removed one of the drives from the computers and tried to gain access by installing as a slave drive... you can see the files on the drive. Virus scan from a working computer says it is clean. ANY IDEAS???

 

Hmm. We've had a couple of posts along the same lines lately.

Can you determine what update was installed that might have caused this phenomenon? Probably the easiest way is to sort \windows by date and look at the $uninstall directories, and \windows\system32 files by date to see whats new.

 

While the MS KB article, 'The Password Is Not Valid' Error Message Appears When You Log On to Recovery Console in Windows XP doesn't address your exact problem, it may point you in the right direction since it deals with "changes to the way that password keys are stored in the registry. "