Need some advice

I am having pb heartbeats stopped kicks for some time now and it is deffinatly anoying the crap out of me. Punkbuster says it is about your firewall/antivirus, I have tried shutting down my avg firewall and also tried making an exception for pnkbstrB & A at the firewall. tried this also with the windows XP standard firewall.
so, I want to try a diffrent antivirus. Recommend me anything good & free.
Thanks, greetz!