I'm very sorry for the trouble here! This generally means that your OmniFocus database has grown to a size where the iPad runs out of RAM during the sync. When we're grabbing the entire database from the server, it uses more memory than a 'regular' sync, where we're just grabbing the recent changes.
If you try the steps listed on the first page of
this thread, they'll help you use the Mac to reduce the size of your OmniFocus database as much as possible. That'll make it more manageable for your iPad.
We're also happy to help if you contact our Support Ninjas via
email or phone (800.315.6664).