mm's dashboard

I just installed the trial of Sunbelt Personal Firewall less than a week ago. I noticed it's slowing down all of my media badly. First I found it was making the audio on AVIs and MPGs (stored locally on my hard drive) skip badly. Then my wife noticed YouTube videos skipping badly. Today I tried listening to some MP3 samples on Amazon and they skipped badly.

With any one of these tasks, the moment I right-clicked on Personal Firewall and disabled it, the media played fine.

I'm running XP SP2 with 2GB of RAM. I tried all the obvious things -- rebooting, shutting down other unnecessary programs, etc.