quote:
Originally posted by SonicSam
Start > Control Panel > Add/Remove Programs > Add/Remove Windows Components
Uncheck Windows Messenger then click Next 
Hope that helps!
Provided it is listed there (in some configurations it is not listed there), this will only remove it from the menu's, it will not uninstall anything
quote:
Originally posted by Animal
did you try ' msconfig ' an go into the startup tab?
will not work. There are more things going on than a simple startup entry in this case. Also msconfig is not a good tool to alter startup entries permanently, despite popular believe.
quote:
Originally posted by Animal
bt you can ' Hide ' it. click on "Set program Access & Defaults " an click on Custom an uncheck Windows messenger
This will not 'hide' it. This will make it not your default choice for an IM client and not listing it in some lists which Windows uses to present you with a choice of IM's.
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As beamykitty pointed out, to properly fix it so it doesn't start up (seemingly) randomly anymore and only when it is actually needed (some addons require Windows Messenger to run!), see:
CookieRevised's reply to I am about to rip my hair out over MS Messanger