Trouble playing DOWNLOADED xbox original.

I recently bought a new xbox arcade after my old PRO broke. I just popped on my old harddrive onto my new arcade and everything was working fine. Today when I tried to play Halo: CE which I downloaded from the marketplace it would not play. Anerror would pop up saying "Cannot play Halo:CE", or something like that.

Any suggestions, solutions. Help would be appreciated, Thanks.

OK, new question. I figured out that the games were downloaded under my brothers account, Microsofts DRM policy probably keeps DLC with only the person who downloaded it in the case of a new xbox. Anyways, anything I can possibly do to get the stuff on my account?GamespotWii