I have a FR610 and I had noticed lots of messages in the FR610 forum about people failing to update the firmware on these watches. I had the same problem myself and had to use a friends Apple laptop to make it work. The reason for the failure seems to be that I'm running Garmin ANT Agent under VirtualBox. I suspect that this was the reason for some of the other reported failures. I now have a similar problem when I wore the HRM for the whole night in order to do HRV stress testing. I typically wake up after around 5 hours of sleep to go to the bathroom and at this point I turn the thing off.
Today I slept 10 hours without waking up, so I had 10 hours worth of HR R-R measurements in the morning. The file is rather huge, so it's of similar size as a firmware update. It seems like I simply can't transfer this from the watch, since the fitness data transfer never gets past 70% before it fails. I was wondering if anyone else has had similar issues and figured out how to deal with it? I'm using Windows XP under VirtualBox 4.2.4 running on Fedora 16. Everything has the latest updates applied.