Not sure this is the right forum. If it isn't, I'll close the topic.
TLDR at the end
Here's the situation. 360's videocard failed. I was going to retire it anyway because the dvd drive is iffy and I have another one of the same model anyway. So I swapped hard drives, tested a game or two, did the license transfer, reinstalled all my DLC, etc.
Have a game that's installed to the hard drive (which I always do). Optical drive recognizes it fine on the dashboard. Launches fine. Drive sounds healthy. Drive stops spinning once the CD check completes successfully just like it's supposed to.
Load up a save from the game I was playing prior to the other console fritzing. Inside 5 minutes the game either freezes or I get the pop up message saying "disc is unreadable." The xbox has long since stopped reading from the disc by the time this happens.
i've cleared the system cache, uninstalled it, reinstalled it, played with and without the hard drive and I have no luck with any of this. Thusfar, no other games have this issue and the game in question didn't have any issue on the last console, nor is the back of the disc smudged.
Microsoft support isn't any help with this, nor is their support website. All google really produces are extremely rare instances of someone mentioning this phenomenon on a forum and not really getting any answers.
So my question is this:
What are known causes for a console to give a disc read error even when the drive isn't active?