I played the heck out of my original purchase of FNV. I eventually started getting so many disc read errors that I decided to purchase the game from Xbox Marketplace so I could play it from my harddrive without the need for a disc.

But now it crashes every 5 minutes. I even got one crash where it told me there was a disc read error and I should clean my disc, even though there's no disc!

I love this game. I've got over 600 hours in characters that I still have save games for! So probably over 800 hours total.

Why is the XBox Marketplace version crashing so much? Bethesda, please help!

There might be a problem with your HDD, take it out and give it a blow clean then put it back in and try again.
The error messge "disc unreadable" seems to be more of an Xbox problem when it's trying to read the file from either the HDD or the internet.

This was wrong

Fixed it. I cleared the system cache, and the game runs fine now.