How do I disable Windows Messenger in Windows XP?
You can keep Windows Messenger (uninstalling it WILL probably hurt your system - but read Uninstall Windows Messenger in Windows XP if you really want to do it), but prevent it from loading when the system starts:
First method
In Outlook Express go to TOOLS > WINDOWS MESSENGER > OPTIONS > PREFRENCES and in the general area uncheck both "Run this program when windows starts" and "Allow this program to run in the background." After doing this IM does not load on startup and Outlook Express loads as usual.
Second method
If you're running Pro, you can use GPEDIT.MSC to prevent Messenger from loading. Otherwise, even disabling it in startup won't cause it to "always" not run. Outlook, Outlook Express and some MS web pages can still make it load.
Start, Run and enter GPEDIT.MSC
For "per machine" restriction, go to Computer Configuration, Administrative Templates, Windows Components, Windows Messenger. For "per user" restriction, go to User Configuration, Administrative Templates, Windows Components, Windows Messenger.
You can now modify whether it starts initially and/or whether its to run at all.
Note: Outlook and Outlook Express will take longer to open, unless you turn off Messenger Support. In Outlook Express it is in Tools, Options, General tab. In Outlook it is in Tools, Options, Other.
Third method
Save and run http://www.dougknox.com/xp/scripts/xp_messenger_autorun.vbs THIS script by Doug Knox. Navigate to where you saved it and double click the file. A confirmation dialog will appear and remind you to log off/back on or restart your computer. This script can be viewed in Notepad or any text editor, as to the specific Registry key and value that are updated.
This version eliminates the startup delay in Outlook Express when the Contacts Pane is used.
Should you decide to undo this "fix", an undo script is available http://www.dougknox.com/xp/scripts/xp_messenger_autorun_undo.vbs HERE. Follow the directions, as above.