My PC with XP Pro becomes super slow after idling for a while. I checked the processes and found msmsgs.exe took 95-99% of my CPU time. I don't have e-mail or IM software running and my antivirus software is up to date. I have turned on my firewall as well. What could have caused msmsgs.exe to start up on its own? Am I hit by a virus that even the latest antivirus software can't detect?