A small part of me wonders why this is a shock. For years we have been told to disable AV software when installing programs because of how they can cause issues. Its exactly the same with running them. The first thing I look at when serious issues happen with software is the AV software. Remove that shit or do a fresh install exactly the same but without the AV software and see how things go.
But the other part of me says I have only had one real issue with AV software screwing with things. Diablo II was the only game, that when installing, I had to disable my AV software otherwise it would take 50 times as long to do so. Yeah, all it did was severely slow down the install. After installed there were no issues. Because of this (as i assume others have never had issues with AV software screwing with programs) I can see how some can overlook this problem.