So this is a strange problem and I'm pretty sure nothing can be done about it, but anyways:
I recently bought a refurbished Xbox (and older one that I believe is an Arcade) to replace an Xbox that I had - but kept the same hard drive and everything else.
I went to play Forza Horizon, a game I downloaded off the Xbox Marketplace, but I got an error message saying that the disc was unreadable. I went to the storage part of the settings on the dashboard and found that one of the Horizon files - my singleplayer save file - was corrupted. It's strange because the multiplayer portion of the game was not corrupted and that will still load all of my cars and whatnot. I would think that the multiplayer part of the game wouldn't work either considering it consists of a lot of the same memory that the singleplayer would use, but I've never had a corrupted file before so I guess I don't know how they (don't) work...
So after I found that out I went through my other games in storage and found that the only other game that had corrupted files, and a few of them as well, was Modern Warfare 3, but I haven't tried playing it yet.
I know that most of the time files are corrupted due to doing something with the Xbox while data is being saved. But that's not the case here...at least I'm pretty sure it's not. I was just playing both of these games before I bought the refurbished Xbox, and I'm not one to just randomly shut off my Xbox while data is being saved.
Has anybody else ever had this problem? And is there a way to fix this?