Win7 64bit computer won't recognize my UFX II.

Changed ports, uninstalled/reinstalled drivers, multiple reboots, CC and 'normal' mode - nothing is helping.

UFX II sees the host (yellow light lit), Win7 sees the UFX in Device Manager (w/a yellow caution), TotalMix won't start - I can choose the layout (right clicking the icon) but the "Initial Device" area is unpopulated and nothing happens after choosing either layout.

Under Device Manager, UFX II, General tab I get this text:
"Windows cannot verify the digital signature for the drivers required for this device. A recent hardware or software change might have installed a file that is signed incorrectly or damaged, or that might be malicious software from an unknown source. (Code 52)"

This is an air-gapped computer with no direct internet access.

The properties window for the RME UFX II, Driver tab, shows the overall Digital Signor as RME GmbH but none of the individual driver files show as being signed.

There is no error message from the installer - it states that the drivers were installed correctly. I've looked around the forum but didn't see this problem addressed for a PC, only for Mac, and it didn't help.

Thanks in advance for any help with this.