It seems like Windows Live Messenger 9 beta is having some problems, The Inside Windows Live Messenger group provides a solution for the following two problems.

Notice: Sign-in problems for beta users that block a group

An issue has been discovered in the current Windows Live Messenger beta that may leave users unable to sign-in. Only a very small number of users may encounter this issue but wanted to proactively message this to the community.

To avoid the issue yourself, please DO NOT block a group and then leave the group. If you plan to leave a group, please unblock it first. Following this precaution will ensure that you will not be affected by this issue.

We are currently working hard to fix the problem and allow those customers who have been affected to once again sign-in to the Messenger beta.

Thank you for your time and for participating in the beta! We will post more information about this issue when it becomes available.

Error 810003c1 while signing into Messenger

Some beta users seem to be getting an error 810003c1 when they try to login to Messenger. This error can be caused if the region setting for your account is not set. If you are seeing this error, please go to https://account.live.com/EditProf.aspx and make sure the Country/Region field is set correctly to your own country.