To answer some of your questions: I have been signed in as administrator when attempting to plug in the keyboards, and I have been plugging them directly into the usb ports on the machine (not through an extension line or hub of some kind).

I will generate and attach a dxdiag.txt file when I am in the lab tomorrow. (The weather in the Northeast kept me home today). I'll also try your suggestion of unplugging the other usb devices attached to the computer, though I believe the mouse is the only other usb device.

I'll let you know how it goes. Thanks for the suggestions!