In the last week, I tried starting up with Reach again and found a bizarre bug.
Anytime I start up the game, it runs perfectly fine. I can play a single match of Firefight, MP, or whatever I want, and everything works, game ends, credits get tallied and everything is right with the world.
The second game I play (again on any game mode) plays perfectly fine, no trouble loading or anything, but once the game ends and it fades to black before the credits screen, I get a disc unreadable error. Every time.
It then boots me back to desktop and I can boot up Reach again, but this time the first game I play will give me the same error right after the match. I can eject the disc, turn the system off, whatever, but it will keep giving me the unreadable error after every first game.
Then, I come back a couple days later, and it goes back to how it originally was, where I get one full game, then the second game craps up right before the credits screen.
Weird, right?
Anyway, I have done the following:
-Play on TU and non-TU playlists
-Play solo games
-Try my friends disc
-Uninstall Reach and try again
-Reinstall Reach and try again
-Clear entire cache
-Delete and redownload all DLC
Note that every other game on my 360 works fine, including Modern Warfare 1, 2 and 3. Those three games cover the old disc format, the old discs with the anti-piracy stuff on them, and the new disc format, if my research is correct. No other game has giving me the disc error in years, and even then it was because the disc was all scratched up (which neither of the discs I tried were).
Also note that as of a month or two ago, the game ran perfectly fine, leading me to believe that it is something TU related.
If anyone has experienced something similar, or has another suggestion for what I can try, please let me know.