Hi - I don't know if you are still looking for an answer but I might be able to assist you if you are still searching. I have a Pro-Form GL36 as well and have had this same problem - a couple of times. The first time I changed the batteries in the console and the last time I removed the console and ensured there was a good connection at the wire connector. If either of those don't work check the wire connectors down below the pedals on the inside of the bike. After that it sounds like it may be time for a replacement console ...
Florida Mike, December 2008