I've tried all the steps in this article:
...with no luck and now I'm stuck with a game I paid for that I can't play. :/
What game are you trying to play? Halo: Combat Evolved
Is it a disc or downloaded version? Downloaded
What type of console are you using? XBOX 360 Original
What size HDD are you using? 250Gb
What error code or message are you receiving? "The game couldn't start. Try downloading the game again. For more help visit www.xbox.com/support"
On a side note, I've also tried playing another game "Star Wars KoTOR" and I've recieved the same error message.
Thanks in advance for the help everyone!