Eject the disc, check for dirt/scratches on the surface. Clean with a soft, lint-free cloth and a very light spray of Windex and try again. If you are having the same issue with any of your other discs, it could possibly be that your DVD drive's laser is going out if the discs appear to be undamaged.
That's a true bummer. Sorry it isn't an easy answer.
FWIW, I had a similar problem with a game disc of my son's that was working, and then after he ignored the game for a month or so then went to play it again, the Xbox didn't even recognize it as a disc. I examined it closely and didn't see anything wrong with it at all. After being told I could get a replacement disc from the company (for almost as much as a brand new copy of the game) and figuring it was a lost cause anyway, I attempted a couple of different things. One of the things I tried did eventually work, but I found out later that a much simpler solution had been available.
I won't list what I did since you would likely think me crazy, but the alternative answer (and one I tried with success on another game my son later damaged) was I took the discs to the local GameStop and politely asked them to run the discs through the big polisher they use for cleaning up and polishing the discs for the used games they sell. They polished them for me and then were even nice enough to put them in one of the store's consoles and see if the discs would read. It turns out that even though I couldn't see it by looking at the discs, the very top surface layer on the data side of the disc had gotten damaged. The polisher took care of the problem, and over a year later they still work just fine. If you have a GameStop near you or another place that sells used games, you might see if they would do the same for you. Another option would be to check their stock of used games and see if they have a copy of the game. I actually broke my disc for Dragon Age: Origins Ultimate Edition at one point, and I snagged a used copy of the base game at GameStop for $5.00. Popped it in and all my saves load, and all my DLC from my original copy of the Ultimate Edition works just fine since the DLC was all loaded on the Xbox from a second disc that was not damaged.
I don't know if any of my suggestions will help you out, but I hope so. It's really frustrating to have a console game you want to play only to find out that the discs aren't working. My son is eight, and not always as careful as I think he should be with the discs, so it's not an altogether uncommon occurrance for me. Fortunately, these little tricks plus a few of my own more... um... creative solutions seem to keep things running most of the time. :catvery-happy:
Luck to you!
How very odd! I play all the DLC with no problems, and it was completely installed from the second disc that came in the Ultimate Edition set. In fact, I then copied all of the DLC packs to a flash disc that contained my game saves and took it with me when I visited my daughter at college. I played my saves on her Xbox without any sort of problems even though SHE only has the base game with no DLC. All of my content worked, so... I'm stumped.
Only other thing I can think of is - do you have the latest Xbox Live game update for Dragon Age installed? I'm not sure which patch version of the game it is, but is supposedly corrects some issues with the DLC. <shrug> What you describe is a new one on me. :catfrustrated: I just can't imagine...
