I had a quick google, and the first site brought me back to here:
http://shoutbox.menthix.net/showthread.php?tid=87879
And the second link, was of course, yours.
I think possibly deleting the folders for your contacts seems like a good idea, and if that doesnt work; uninstalling your firewall?
Like, just to see if that works, and then put it back on?
Other option, of course, is to just not use the beta.
Im running it just now, and i can logon fine, but when i put Plus! on, my chats don't flash.
I think just using the first beta might be a good idea, or going back completely to the old one.
[edit]
I take that last bit back. It appears the betas been released as RC1, so theres no going back..
The only thing i can think of is talking to Microsoft. Or completely formatting, and installing JUST messenger, and see where that takes you..
Adam.
/ 
