I have had similar problems and though it was a software thing turned out it was actually the cable. The connections on the alligator clip are a bit dodgy and they are just a series of spring loaded pins that slide in and out. You should check to make sure that they are all working properly as I have one that occasionally sticks down slightly. When this happens I can hear the watch connect and it charges fine but as soon as I try to connect in the app I get a com port error. I ended up taking apart and then freeing up the stuck pin. once I did this all good no problems. It has happened to at least one other person that I know of.
shame that the GW 60 doesn't have a better connection system but I guess that is what you get with a cheaply designed watch.

Mathew I'm guessing the cat gets as frustrated with it as we all do.