Well the Vista firewall doesn't have outbound protection enabled by default, so if you haven't enabled outbound protection (which I feel is essential) then it shouldn't be an issue.
My only other concern is AIM and if it is supported (I don't use the Instant Messaging shield as I don't use IM applications), that however shouldn't stop it from opening or running at all as your opening post stated "I even turned off the scanner to try opening it. That didn't work."
So to me there appears to be some sort of conflict going on if it won't open at all.
Have (or did) you another Anti-Virus installed in this system, if so what was it and how did you get rid of it ?
Are you using avast free antivirus version 5.0.507 ?