Parallels Ethernet Adapter requires reinstallation after every reboot in Win 7

This is odd and I've poked around and haven't found a solution here or in the vast tubes of the interwebs.

I am running Parallels 6.9.11994 on a Macbook Air with Windows 7 Enterprise N installed. I have a similar setup on a MacBook Pro (two licenses of Parallels and Windows). On the air every time I restart the Windows 7 VM I have no network access. I have to go into Device Manager, uninstall the ethernet adapter (leaving the driver...learned that the hard way), and then scan for harware changes. It reinstalls and all is right with the world.

I have tried reinstalling Parallels and no change. Trashed the VM and reisntalled that, still no change.

Any ideas? At this point it's a mere irritant, but I would like a resolution.

Tory