tunneling not working with windows 7

I've used tunneling for a while with XP and it worked great. But now my machine has been upgraded to windows 7 and it no longer works. I get the following error:

Error while tunneling the connection.

Administratively prohibited (open failed).

It would appear the tunneled machine is rejecting the connection to the destination machine, but this all worked fine in XP, so something about Windows 7 is probably causing this Anybody got any ideas how to resolve this???

Using version 4.3.5 (Build 1463) and the Commander interface.

Yes, the error means that the tunneling machine rejected the tunneling.
So it indeed does not look like it is related to Windows 7.
Any chance you can post log files both from Windows 7 and XP?