The Dragon Age: Origins DLC “Return to Ostagar” has been removed from Xbox Live Marketplace by the BioWare this morning. According to the updated DLC title , its having a bug which brokes abilities of certian class in the game.
According to the moderators of BioWare official forum:
Hello Dragon Age fans
This morning a title update on the Xbox 360 for Dragon Age: Origins was made available in preparation for the release of Return to Ostagar. This title update introduced a previously undetected issue that causes specialization classes to not work correctly in Dragon Age: Origins. We are removing Return to Ostagar from Xbox Live until the issue is resolved and are recommending that you do not download the title update. If you have already performed the update, we apologize for this and are working hard to ensure a fix is available as soon as possible. We will provide more information to you when it is available.