Alright, so I have two problems and I'll detail them both for you.
The first is with Trials HD. I purchased this game on 4/22/2011, and it freezes when I start it. I start it up, and the sound for a menu opening occurs, shortly after the menu screen for downloading an update appears, but no matter what I press, it doesn't leave this screen. I have deleted/redownloaded as described in this thread many times to no avail. In case it helps, before it started freezing it would just show "the game isn't working, please download it again" or something like that.
My other problem is Super Meat Boy. I purchased it on 10/24/2010, and didn't have any problems until the thing with Trials HD occured. I had to update SMB again, and now whenever I start it up, right after it shows "Xbox Live Arcade" it goes back to the game library screen, with no error message. Again, deleted and redownloaded this many times as suggested.
Any help would be appreciated.