Anti-Virus' often accidently recognise safe programs as virus'.
This is why I don't have Anti-Virus' installed on my PC.
It's a tactic against the less computer-savvy people, making them believe every corner of the internet is a threat - that or it really is an accident...
Yet I run into an actually dangerous virus every few months, contrary to what people will have you believe, the internet is a pretty safe place if you're careful enough.