Shoutbox

Should be possible, but it isn't Plus..

1) Check the options:
  a) Autologin
  b) Save password

Create a new task with the task scheduler which starts MSN Messenger

Logging out is a bit harder, but you can try a cool named "Pskill"  (http://www.sysinternals.com/Utilities/PsKill.html)

Should work!

If not, try "AutoIT" combined with the Task Planner AutoIT is a scripting language which can create macro's..