Open Task Manager (Start - Run - taskmgr.exe)
Go to processes tab and verify "msmsgs.exe" is not running. If it is click on the process and choose "End Process"
Go into your Program Files folder.
Rename the Messenger folder to "MessengerOFF"
If you are unable to rename the folder in this manner then boot to safe mode and make the change.
Why wouldn't you just; run > msconfig.exe, go under "Startup" and Deselect messenger so that it doesn't automatically boot during startup?
I don't know about any of you, but that worked perfectly fine for me, and is certainly easier than having to reboot in safe mode in case you cannot rename such file to the above.
Does "Steve" want to comment on this?