[Steven Haines]

I have a similar but not identical problem. I am syncing via MobileMe.

If I leave OmniFocus open but sitting in the background, syncing usually doesn't work when I open the fast application switching screen and tap on the app to bring it to the front. Mostly, I do not get a timed out error. Instead, the sync graphics just continually spins in the toolbar. If I quit the application and reopen it, the sync works without a problem. The issue seems to be related to placing the application in the background rather than dimming the screen.