Rob, the X5 uses the same IPTV file format as the X7. When I made a list that I posted for the X7, I mentioned that it should work with the X5. Plus I posted "An immediate "data error" message indicates a bad url or no connection available. A latent "data error" message indicates can't connect right now, but might work later on". I would think that you're getting this error.
Hope you get it working again.