Microsoft's Anti-Spyware program is causing troubles for people who also use Symantec's Norton Anti-Virus software; apparently, a recent update to Microsoft's anti-spyware application flags Norton as a password-stealing program and prompts users to remove it.
According to several different support threads over at Microsoft's user groups forum, the latest definitions file from Microsoft "(version 5805, 5807) detects Symantec Antivirus files as PWS.Bancos.A (Password Stealer)."
When Microsoft Anti-Spyware users remove the flagged Norton file as prompted, Symantec's product gets corrupted and no longer protects the user's machine. The Norton user then has to go through the Windows registry and delete multiple entries (registry editing is always a dicey affair that can quickly hose a system if the user doesn't know what he or she is doing) so that the program can be completely removed and re-installed
I'm sure this will be fixed quickly, but I would double check any malware results from MS Antispyware if you have Norton.