I've unlocked the device. I've enabled Developer options, and USB Debugging is enabled.
But with USB Debugging enabled, I don't see the Nexus 7 in Device Manager under "Portable Devices". The only way I can see the Nexus 7 under Portable Devices is if I disable USB Debugging, but even then the Nexus 7 shows up with a yellow "!" indicating that "This device cannot start (Code 10)".
How can I get the PC to recognize the Nexus 7 with USB Debugging enabled?