hi..
MSN has been having problems lately and according to my friends from different parts of the world it seems to be spread all over (not sure how much though, and different times as well).
All you can do is keep trying every now and then until it's ok. It didn't take long for me to be back online.
BTW, have you tried http://webmessenger.msn.com ... I like it :) ... it could work for you in the time being.
Ciao for now.