Ahhhh, sorry I completely misread the post and thought you'd said firewall rather than AV, probably because I can't think of how the AV system would or should adversly effect the notifications.
The only thing I can suggest is to go through the logs from the AV scanner, but obviously depending on which AV software you're using this might be impossible. I think Norton has some level of logging its activity, but I have a feeling a lot of them don't really both, which is a bit of a pain.
Sorry I can't think of anything more helpful.