TypeError: tcxDocument is undefined

I got this error when trying to load a bike workout from my Garmin 910XT.  Lately I've been having other issues  uploading individual workouts from the training page and the import from Garmin button.  It seems to take a long time when it does work then I get a message about a script being busy, I need to press enter to continue.  I can upload from the Upload button and selecting workouts just fine.  However with this technique I have to go back and add comments.  I just update my Garmin Communicator.  I am using current level of Firefox.  Any suggestions?