Sounds like the Lockup Torque Converter. My car did the same thing last year. Find out if the Transmission fluid was flushed in the last 2 years. Find out if at the same time he had the Transmission filter changed.... If it had a flush with out a filter change, gunk from the old filter could have gotten into the Lockup Torque Converter and messed things up. Thats exactly what happened to me and the shop that worked on it has seen that same thing a lot! My car would sometimes start in Neutral and sometimes it wouldn't.
Sometimes I could unstick it by starting in Neutral, reving the engine and while it was reved put it into drive, if I got the engine speed just right it would lerch forward and start moving. After that it would normally drive fine for a little while.. If it is taking to a shop, it needs to be a transmission shop. Most shops (at least around here) will send it to the Transmission places cause they don't want to work on them. LOL!! At least that was my experience.
Good luck and please let us know how it goes.
Heber