help with xbox

i keep getting this screen saying the disc cannot be read it may be scratched or damaged. im not sure its the game because i just bought it (fable-the lost chapters) and when i first played it that screen came up and it keeps coming up. it could be my xbox. i was watching a dvd and it kept freezing then i watched it at my friends and it didn't. and sometimes my xbox mistakes xbox game for dvds and says i need the dvd playback kit to play this dvd?
any suggestions how to fix this?
-now my xbox is making a loud humming noise when i play a game(just unmodded it and deleted mod files) this has never happened before when i'v done this
-still having dirty disc error

 

prob need a new disc drive, one of my xbox's before did that, new drive fixed it.

 

where can i buy it and how do u install it?

 

ebay? its easy to install, just take apart your xbox and the disc drive will be right in front of you and just unplug that and plug the new one back in.

 

thanks,
i also burned the game to my xbox and it works fine now.
i think i'll get a new disc drive though

 

how do u open an xbox, and are there any other places to buy the tray, i checked ebay there are none

 

pictures on how to open your box, just follow the link!
http://www.xbox-scene.com/articles/open2.php