My dad upgraded norton antivirus on his computer 2 months ago and during the install something got corrupt and ****** everything on the computer. None of the .exe files would work and you couldn't reset it to another time or date. I let the computer sit for a day turned off brought it downstairs booted it in safe mode, and everything worked just fine. Restarted the computer and everything was fine. That is the only problem I have had with norton in years.