[reggoboy]

it's also possible there is some kind of error with reading the database file (like the database file being locked/inaccessible)

Good point. I should add that on at least 2 occasions I saw some error about error opening a file. I ignored those errors because I think they came after the "error sending database" message, and so I figured they were a side effect of the sync failure. 

If this happens again, I'll screen shot the other message, and see if that helps with the one issue.

Thanks!