HI, I have experienced that after putting Evo X on the Hard Disc (See my Sticky in XBOX Mod Discussion to be able to install it without linking to a PC) that some games will not load at all off disc!
I have found the Solution
Edit your Menu.ini with the bold link, place it under the root menu :
Item "Run Game From Drive","d:\default.xbe"
Item "MS Dashboard",@3
Section "System Utils"
Item "Flash BIOS",@1
Put the disc in the drive then select.
This may also work to be able to play games from CDR!! I need someone to test.