FIXED!!
A complete n00b error - I apologize.
Apparently ESET NOD32 was blocking communications. After disabling it temporarily, I was able to communicate with Flirc, update the firmware, and configure a XBMC map with my Harmony Ultimate One. I then saved the config on my network, went to the HTPC system, disabled the NOD32 temporarily, loaded the driver, and loaded the custom config I had saved.
I also learned that Flirc will not work when plugged into a USB 3.0 port, only a USB 2. So, I had to relocate my external DAC to a USB 3 port, and it works fine there.