Windows Media Server and VPN issue

Hi,

I have a server that is both a Media Server and a VPN Remote Access Server.

I can VPN fine into the machine if there are no Media clients trying to
stream content from the Media Server. The minute a client connects to the
Media Server by VPN connection hangs i.e. no network traffic goes thorough.
If I disconnect the VPN connection and reconnect - the authentication and
authorization steps complete but no futher traffic makes it though the
connection. The minute the last media client disconnects from the media
server the VPN connection starts working fine again.

Note: This is not a network is saturated type issue. There is lots of extra
bandwidth on the netcard/network. Also the CPU's arent maxed out. I am able
to access web site on the same machine simultaneously. Only VPN traffic
doesnt seemt to get through.

Can anyone tell me why this is happening and how can I work around it so
that both things work simultaneously.

Thanks