Ran Avast now can't get into XP!

I recently replaced a hard drive for my uncle and put XP Home Edition onto it. He asked me about antivrus software and I recommended the free Home version of Avast, having used the Pro version at work with no problems at all.

I sent him the link and he installed the program and then ran a scan. He said that THOUSANDS of files were quarantined/deleted and that when he rebooted the machine XP came up with a login dialogue with a username of “OWNER”. Of course, he doesn’t know the password!

As he only had the default user account setup in XP, it used to just boot right up without any passwords or other intervention. We tried entering a blank password to no avail.

Please can someone give me a clue as to how I can get around this to save another XP reinstall?

Thanks in advance.

Well… if your system is deeply infected, I really think that reinstalling will be easier and safer.
Anyway, you can try overinstallation that can solve the problem and you won’t lose your programs, settings, data, files, etc.

Just choose ‘Repair’ installation of Windows and install ‘over’ the old installation.
http://support.microsoft.com/default.aspx?scid=kb;EN-US;315341
http://support.microsoft.com/default.aspx?scid=kb;en-us;Q314058
http://www.webtree.ca/windowsxp/repair_xp.htm