To determine what version you're running:
- With 1.x, click on the Dropbox icon in your menu bar and choose Preferences > Account.
- With 2.x, hold down the Option key and click on the Dropbox icon in your menu bar and choose Preferences > Account.
I know many Curio customers use Dropbox and it looks like lots of bugs have been fixed recently, so if you're not on 2.0.6 then make sure to grab the latest version.
On a related note, Curio 8.4.1 and above support a new, much easier technique for syncing your Curio application support folder across multiple machines using Dropbox.