This IS the solution!
Amazingly poor coding by Turbotax -- they apparently built the system profile based on hard drive signatures. Idiots. Instead of messing around with telling people to reset their IP address, THE FIRST TROUBLESHOOTING STEP should be "CHECK FOR USB-ATTACHED DRIVES".
I wasted an hour with tech support, saw this while on hold with their useless script-monkeys, and problem solved.
THANK YOU SO MUCH
