I had a bizarre experience last year. Suddenly my AOL dial-up stopped being able to make a connection (I use AOL for emergencies when DSL is down.) It started working again however when I un-installed Norton Anti-virius. I tried again to make sure - re-installing Norton, then AOL 9.0 could not make a connection again. I tested this multiple times. This was a total pain and at first I assumed the problem was the XP service pack, but it wasn't.
I switched to McAfee Anti-virus which AOL provides for its users now for free and everything works great.
My carrier was Bayou Internet, sometimes it would take me an hour to dial up. They bought out World Net and it was never the same. I'm with Bellsouth now and no problem with dial-up. My daughter got tired of not being able to get to me by phone because we only had one phone line, so she got me a seperate line put in. My sister was on AOL and all she had was problems with it. I have a stack of AOL disks that they send in the mail for free hours. My sister said not to use them.
I'm pretty sure it's the Norton that is creating all of my problems.