The Messenger servers and the new protocol are having hickups since a coulpe of days... It will be fixed when it will be fixed, meaning: patience, nobody can do anything about it...
Also, please search the forums before making threads (or at least simply look at the latest posts page in this case). This issue about connection problems has been posted gazillion times already and the answer is still the same: nobody can do anything about it, you need to have patience or revert back to MSN Messenger 7.x which uses an older protocol.
NOTE:
uninstalling and reinstalling Messenger and/or Messenger Plus! will have absolutely no effect! (just as it has absolutely no effect in many other cases; reinstalling isn't the magic fix for everything.
In fact, it is a fix for only a very very very little amount of problems... and that goes for almost all software)... (and if it had an effect it would have been just pure coincidence)... It is the servers and the new protocol which is having troubles.