Hello,
This is the error you're getting?
We were unable to sign you in to Windows Live Messenger, possibly because of a problem with the service or with your Internet connection. Please make sure that you are connected to the internet.
Error code: 81000306
It isually just lasts for some minutes, but if it's persistent, you can find step-by-step troubleshooting here:
http://messenger-support.spaces.live.com/blog/cns!8B3F39C76A8B853F!13932.entry
Hope it helps