I have the exact same problem. After I run outlook and closed it or sended an e-mail it runs many copies of OUTLOOK.exe and one named Addinmon.exe. It all runs in the ussename you are curently using and it can be stopped if you continue ending those problems. I had this problem now two times and first I thougd it whas a virus.
My gues is that ZoneAlarm is causing this problem although I am not sure. My question is if you also have zonealarm running?