You could just restore a backup.
What do you mean vendor? Who decided to do a system restore? Have you booted into the BIOS to see if you are actually booting into the hard drive?
Did all of the computers get this update. All of our computers got all updates and none were corrupt and none were known to be corrupt.
You can also try throwing the question on
www.experts-exchange.com under a few categories including viruses. But, no one ever does this so it is probably a moot point.
Do you have a reputable computer repair shop you could take it to? I would be running some serious virus scans on any computer that is working. Malwarebytes, etc.
Easiest thing would be to just restore from a backup.
