Well, now that you mention it.. I think I remember seeing some issues with PLugin CG and theora plugin.. How is the order of your plugins.cfg file? Ensure you list Theora plugin last maybe? THough, I am not sure it was the CG plugin, but something odd with the plugins.cfg file.
Remove all plugins that are not needed in your app in the plugin.cfg. Then, systematically add them back to isolate where it fails at is one way to find the problem possibly.