I recently migrated to Windows 7 RTM. I had been using Windows 7 RC with MSN
Messenger 8.5. Whenever Windows Live Messenger signs in it signs out within
seconds.

This does not happen on my home network, only my work network.



I tried to uninstall and install MSN MEssenger 8.5, but when I start it, it
tells me I have to upgrade to a newer version and it does not work.

I have no problem running my other apps or accessing the Internet from work.

Is there something I need to configure to make this work?

Here the same problem.
Work network stays connected while appearing offline and disconnects when switching to online. (LAN, user@somedomain.com)

Another wierd thing:
When I use a msn account (hotmail) at work it looks like I stay
connected

At home everything works fine.. (WLAN)