I’ve been watching this mess unfold watching various forums, including BitDefenders own support forums, and it doesn’t look like it’s gaining them any new customers. Apparently, the new update marks needed Windows system files as infected and goes ahead and gets rid of them for you. If you don’t mess up too much, you can do a system restore and disable the AV until a new update is available. Ouch. A lot of people are looking at new clean installs of their OS.
“EVERY file that is trying to run is getting quarantined,” one user, identified as lhmathys, reported. “Windows Explorer and even Bitdefender update itself is being quarantined. Someone really screwed this one up.”