Vista - VPN Problem

I have (or so I thought) successfully set up my VPN connection as to get
E-Mail from work. It "dials" and connects just fine. However, talking to
my network admin, the username and password are getting cut off on his end.
I've walked thru all my settings and he says they are correct. I'm curious
if I've missed something with Windows Firewall.

Any ideas would be greatly appreciated.

Running build 5600 RC1.

Thanks,
Rick