Webpoint, I'm sorry for the trouble this is causing! The main culprit when this happens is a database that has grown large; the phone is running out of memory during the sync process, causing OmniFocus to be shut down.
Are you syncing the phone with a Mac, or using the phone by itself and syncing as a backup?
If it's the former, the tips in
this thread may help you reduce the size of your sync database and prevent the phone from running out of memory.
If you're not syncing with a Mac, the tips in that thread won't work, but our
support ninjas can help get you back up and running again.
(Just in case this is some sort of new syncing issue, I moved your post to its own thread in the Sync forum. If someone searches the forum for "Sync", they're more likely to find it this way.)