Ok, not having the P: drive (TrueCrypt encrypted volume) mounted at the time the converter was examining the running system seems to have been the answer.
Even though I never intended for the converter to deal with that volume, just having it exist as a mounted disk was enough to cause the error in the converter.
I re-ran the converter without that volume mounted and was able to convert the running machine into a VM that can now be used.
Thanks for the help!