Anti-virus software can interfere with anything. For e.g. AVG Free managed to break the connection between Windows Update and the internet. (it took control?? over it, COMPLETELY) Only when uninstalling AVG (it was an old version anyway, it was broken from age) would Windows Update work again. They can even stop the possibility of safely removing external devices because it may or may not be scanning something on the device. Anti-Virus Software needs to take control over your computer and protect it for a good reason, that doesn't stop some software like Avast! or Norton from destroying your intuitive computer experience; pop-ups every few seconds it feels like.