@ jadinolf,
Do you have OA on all your machines or only this one with the problem? I still think ZA is the problem and as Asyn mentioned earlier others have reported problems between avast and ZA (except the ZA firewall). In addition, I believe there is also a conflict with OA and ZA, but you should clarify with them on this. You shouldn't run two third-party firewalls on the same machine. My recommendation is to remove ZA since you have OA.