[derekr]

Hey-

So, this usually means something has gone wrong with your sync database, stored on your iDisk. If you don't need that sync database any longer, just head to me.com, log in, and then delete your OmniFocus.ofocus file in your Documents folder. (To be on the safe side, you might even want to rename it to, say, OmniFocus.old.)

Once that's done, just press the sync button again. Everything should just work.