"As BioWare explains: "Over the April 9, 2011 weekend, some of our Dragon Age: Origins content servers experienced an as yet unidentified failure."
"As a result, users began to experience error messages when attempting to access their downloadable content, indicating that the DLC was unauthorized," it added, saying, "We apologize for the inconvenience and are currently investigating and working to resolve the issue on our end.""
It wasn't just Dragon Age: Origins. Mass Effect 2 on the 360 had the same issues - would not recognise the download packs on the hard drive and refused to load my saved games as a result. Managed to overcome that particular problem by disabling the EA auto log on feature in the options menu and rebooting. As long as you don't automatically log in to the EA server network when you start the game, you're fine.