Overtime, MSN Messenger contact lists get cluttered.
Usually because of spammers, friends that change or lose their e-mail, or contacts you no longer talk to.
Yes, you can organize them into groups, and you can block them. But the MSN protocol and all the evolutions it has suffered have left some serious room for messiness.
Your MSN Messenger unable to remove a contact?
If when removing a contact from the msn messenger chat, you receive an error "msn messenger the server was unable to remove the user from your contact list, please try again." Don't fear!
Get the newest version: Microsoft Messenger for Mac OS X (OSX) and in the login panel, choose "clear account history". (this doesn't clear chat history, so don't worry)
It will help clean up your contact list and all the accounts. It's brilliant. It gives you the ability to choose which contacts you want to add to your contact list.
This is also worth a try:
This tool will connect with the MSN servers, then use your supplied .NET Passport account information to login and retrieve your current contacts list. This data is then parsed for unnecessary contact list "junk" data, which is then deleted. This usually repairs problems related to corrupted contact lists, and it helps to speed up login times.