Anti-virus goes off for forum ads

Alot of the time, before loading the full page, my anti-virus (Avira) will pop up telling me there's a virus, found in one of the ads. When I click delete/deny it then loads one of the ads under the main banner etc. but before the actual forum (next to the 'plenty of fish' ad if we all get the same ads?), so think I've pinpointed the problem to have come from one of those, but then again it could be the main banner ad as that would already have been loaded, however it never happens when I'm in a thread etc. and the plenty of fish ad etc. aren't there.

I wondered if this was actually an issue, or just my anti-virus getting the wrong idea about something that's actually nothing.

 

Interestingly, on my desktop thats running Windows 7 and not Avira, I never get notified of a virus. I'm thinking it's Avira that's causing a problem and perhaps mis-interpreting a part of the advert code or something.

I've also looked in the settings and seems it's a set 'strictness', but it's probably buried so I'll keep going, or install a different anti-virus (shame as it is very good, but seems to get spooked by things that aren't a problem - still, rather that than too much the other way!) .