If you are like me, you hate the fact the there are 2 Microsoft Messenger clients, one labeled Windows Messenger and another called MSN Messenger. Rory had a good thread on how to remove Windows Messenger (which is a pain to do), but it seems to always come back, or is needed for some security patch. So, I have tried to learn to live with Windows Messenger, and remove all program dependences on it. Outlook and Outlook Express seem to be the biggest offenders to starting up Windows Messenger, even though I never ask it to do that. In Outlook Express 6 you can disable its dependence on Windows Messenger thru the Options Form. In the General Tab, in the General Section the last option box is labeled “Automatically log on to Windows Messenger”. If you remove the check, Windows Messenger will not start (but I’ve noticed that occasionally it will come back when you install some OE security patches).
The other, and more difficult to find, source of Windows Messenger mysteriously starting up is Outlook 2003. I just downloaded and install the latest XP SP2 security patches (and a Outlook Express patch) and Windows Messenger started up on its own again. I had to hunt around in Outlook but I finally think I found the culprit. If you go to the Options Form and select the Other tab, the last section is labeled Person Names. If you uncheck the “Enable the Person Names Smart Tag” option, Outlook will no longer mysteriously start up Windows Messenger. The only way I figured out to try this option is that the icon next to the option looks a lot like the Windows Messenger icon. I don’t know how the average person is supposed to know that this implicitly will start up another program, but there is it.