I've seen this before but not for a long time, and yet today a number of people are reporting it
http://www.timetriallingforum.co.uk/index.php?showtopic=109158#entry1507873
So we're wondering why today a number of people are getting their garmin 500s stuck on "working..." In the UK our clocks went forward, so perhaps its related to that.
I've also had the problem where the garmin connect software deletes my ride without saving it. I got around that by not using the garmin connect software, but these products would be more attactive if they weren't so buggy.