If you are experiencing difficulties with playing multiplayer using a Windows 7, and you have already read this thread, there's no solution to your problem at the moment.
However, this problem has been noted and will be fixed as soon as hampa get's his hands on a Windows 7.
It seems as though the TB client and some root-key files in the Windows 7 don't like each other.
Please be patient and try to bear with this inconvenience.