Windows 7: Problem: Remote Desktop through VPN

Hi all,

Searched the internet, forums and tried everything even removing IDT.
And getting a major head ache out of this.

RDP works at other Windows 7 Ultimate x64 notebooks.
But on 1 single notebook the RDP does not work when connecting through a VPN.
(Sony Vaio S-series factory customized i7, 8GB)

The office has a Draytek VPN with an 2003 AD domain.
Other notebooks do not have the problem.

• Remote desktop locally works
• Remote desktop via branche office works (through hardware based vpn tunnels)
• MS VPN connects, network is browsable
• MS VPN -> RDP shows: [Configuring remote session] But after a while connection is denied
• MS VPN -> Fileshares - functional
• MS VPN -> Webserver, FTP server - functional

Maybe one of you guys have a hunch why this specific situation doesn't work?

GPO managed VPN and RDP settings?

Is that Sony Vaio in the same computer OU as the others?

What kind of firewall do you have in place? Maybe an ISA firewall? It took a lot of configuring for us with ISA.