The problem you are experiancing has been an on going battle between Msn services and the rest of Microsoft. Msn messenger causes entire machines to hang when ran as a user. if at any time you updated your machine to have Msn messenger connectivity update 4.6 it will freeze outlook/outlook express for extended periods of time.
To fix this problem go and get the latest version of Messenger and install it on the machine having the problems. Next you will need to run this code to remove the program. you will need a copy of the msmsgs.inf in the messenger folder to remove it. The file can be extracted from the setup files downloaded when installing the program. The other alternative is to make sure that you have an administrative account. The following code can be copied into a batch file and run.
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"RunDll32 advpack.dll,LaunchINFSection C:\"program files"\messenger\msmsgs.inf,BLC.Remove"
del "C:\Documents and Settings\%username%\Start Menu\Programs\Windows Messenger.lnk" /q
del "C:\Documents and Settings\All Users\Start Menu\Programs\Windows Messenger.lnk" /q
rd C:\progra~1\messenger /s /q
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This is also an effective way to remove messenger from Windows Xp if needed.