Cannot VPN (windows 2003 RRAS)

Let me start off by saying that all of my XP clients are working fine
connecting to my VPN server.

Just to Vista and I cannot figure out why I am able to connect to my VPN,
but then it disconnects.
when it's connected, i cannot retrieve email (outlook), cannot ping any
computer on the network.

I turned off all the firewalls temporarily to see if this is the cause, but
no luck with that either.

Searched MS under VISTA for PPTP, VPN etc.......... No cigar.

anyone have any ideas?