I'm using dropbox across several machines - two macs, two linux machines.
All are working happily - except for one mac, where there are 4 files that persistently refuse to update.
In finder, these 4 files have a red X icon. The dropbox menu is stuck on 'syncing' (and has been for about a week now), and has part of an error message saying that it can't write to these files.
In Finder's "Get Info", it says I have read+write access; at the commandline, ls shows that they have -rwxrwxrwx permissions.