After a flood of users clogged their forums, BitDefender issued a statement describing a recent update gone wrong.
“Due to a recent update for Windows 64-bit systems it is possible that BitDefender detects several Windows and BitDefender files as infected with Trojan.FakeAlert.5 .”
It seems BitDefender was identifying even it’s own files as infected with Trojan FakeAlert 5 and sending them to quarantine. The result was a whole boat load of broken Windows installations and systems that wouldn’t boot.
Those smart enough, were able to pick up on the fact that the problem was with the well known anitvirus and not their systems or actual infections. Removing the files from quarantine and turning off the BitDefender Antivirus program corrected the problem. Failing that, use of the Last Known Good Configuration from the Boot Menu or even using System Restore saved many users.
You can follow the 77 + pages of fun here and I do hope you weren’t one of the unlucky ones.