The network connection between your computer and the VPN server was interrupted. This can be caused by a problem in the VPN transmission and is commonly the result of internet latency or simply that your VPN server has reached capacity.
List of Error Codes that you may receive when you try to make a dial-up connection or a VPN connection in Windows 7
It sounds like something on Win7 is interfering with TCP traffic on port 1723, (or the GRE 47 packets), to that specific IP address - that would usually point to the firewall being the culprit.
From a CLI in both Windows 7 and XP:tracert <vpn that's failing>
And paste the results, munge your IP if it shows up, (first couple of lines), and you're paranoid.
What AV are you using, some won't stop interfering even when disabled.
Even though it works OK from XP Mode on the same computer, if your router has a DMZ put the computers IP into it and try to connect to the VPN again from Windows 7, or if you have a separate modem, plug the computer directly into it and try. Bypasses any strange firewall rules in the router.
In Computer Management->Event Viewer->Windows Logs->Applications there'll be the results of rasdial commands, a successful connection looks like:
What do you get if it's not the same, (and the actual event data not a picture, thanks) ?