Fix for error error 0x81000370:
Click Start, then Run, and enter the following: REGEDIT
Now go to HKEY_CURRENT_USER\Software\Microsoft\MSNMessenger
Delete the keys DAConfigVersion and DomainAuthority. Make sure that you don't use/run registry protectors. Restart your Messenger.
and here is the link for error 0x800C0005:
http://www3.telus.net/dandemar/0x800c0005.htm
After this is done you can change you NICK to Happy_Camper
cheers