Trouble loading the campaign missions even though you've installed the second disk

I have the same problem. Bought the game from the via store, I installed and uninstalled the game 2 times both reaching 100% downloaded and the campaign is f***ed up which it won't load the second mission correctly and I can't even most of the online servers.

Exchanged my first one which was giving me a disk read error after the first mission... The second one is worse than the last. I can't load the first mission unless it's from the start, and I have to play it through to try and get to the next mission...
If I try to load the last checkpoint of the first mission it freezes at the transition/screen saver type screen - this is exceptionally frustrating. I've only had trouble like this twice, once with Halo 4 and the other with Reach...

I have had load failures on some days even though our disk is installed. I thought it was a server or internet problem. Actually, we have two consoles. One is running the installed disk version of Reach. The other is running the download version. We have
experienced occasional load failures on both.

Try installing both disks to your HDD, if you not already, Try puting in the MP/Co-op disk in first and load to the Main Menu. Click on Campaign and it will prompt you to insert the Campaign disk (2ND Disk). That may fix your problem, Clearing the System
Cache and re downloading the update may also fix the problem. This is a issue I have never encounted.

I'm not talking about saving stats and such to waypoint, I totally understand when you're offline it won't do that. I'm talking about campaign saving mission progress. finishing missions and even loading checkpoints. If I beat the first mission offline it
doesn't save the fact that I've beaten it so when I sign out and back in it makes me play the first mission over again. but beyond that, even if I have played through while online, when offline it should still load that mission progress. not the stats and
such, but it should at least recognize the fact that I've beaten the campaign and I can load any mission I want. THAT"S where the problem is.