[DerekM]

Do you get an error popup when the documents don't open? If not, can you check your Console log for errors. You can do that with Console.app in the Applications/Utilities folder.

To uninstall OmniOutliner, all you need to delete is the OmniOutliner.app file and if you use the Pro version, the "OmniOutliner Professional.service" file in ~/Library/Services. I'm not sure what else Appcleaner and Hazel would be deleting. And I'd be a little worried about what Hazel is doing unless you are positive it is not doing anything to OmniOutliner the rest of the time.

Thanks