Hi Chris,
Assuming you have rebooted the machine after installing it on 2008R2. I have a few questions.
1. How much memory do you have on that server ?
2.Have you installed the driver on top of an inbox driver ? if so, can you uninstall everything (from control panel) and install back ?
3.Code 10 is pretty generic and might indicate on a corrupted installation from any reason, is there an additional print that follows it ?
4.Can you try WinOF 4.80 that was out a few days ago from the Mellanox website ?
Cheers