Uploading "long" Garmin training files 310XT

I'm finding that I have lots of trouble uploading my long training days. I upload with the UPLOAD function, it says the workout will appear shortly in my training log, but hours later it's not there. I've tried to upload via import workout from the training lot, and it says "transfer complete" but then hangs and never puts the workout in. My shorter workouts upload with no problems, but the longer ones just don't see to show up. I recently updated Communicator in hopes that would fix it, but no dice. Am I doing something wrong? Any ideas? Thanks so much and thanks for all you do!!