I had the same problem, no matter what i done it wouldnt sign on, some m8s were back on but i wasnt able to, tried the lot, e-messenger old msn new msn, restart etc. Then researched alil into the error i was getting and sorta narrowed it down to some missing .dll that msn required, so got a bat file, ran it, sorted the .dll problem and hey presto onto msn, the error was along the lines of temp unavailable and 08003 .... something like that.
Anywayz ive attached the file, may be of use in future. Edit was hoping to attach file, but cant seem to
Edit again: heres direct link
http://www.imzers.com/msn/solve/error-code-0x81000314