I really dont know whats the catch on this but Microsoft Messenger for Mac just decided to stop logging in for one account. I tried to login with a second account and everything seemed fine. The message I got back while I was trying to login with my account was something like “The service is down or I was not connected to the internet”. Of course non of those cases where true. So what I did was to trash the “Microsoft Messenger User Cache.plist” located on User/Library/Preferences/Microsoft. So far it doesnt seem to have lost any chat history or contacts but keep a back up of the .plist file just to be sure.