Windows 7: Live Messenger - hosts file

Running build 7127...and the latest Live Messenger.

4 Users on machine; only one user has a problem using messenger.

Upon trying to login to messenger they are presented with the unable to login error. Click on troubleshoot; and it brings up a hosts file error, as well as a key ports error.

I have clicked on repair, and nothing seems to happen for a long while.

The hosts file is the default hosts file; nothing has changed at all. Cannot log into messenger at all.

Update;



Have now logged user into messenger - but now their contact list has disappeared!

Just wondering if anyone has any ideas on how to resolve this issue?

TIA.