I recently bought a copy of Call of Duty 2 for my Intel iMac. Immediately after I bought it, I used disk utility to make a disk image and copy it to the HD. It worked fine for me and I was able to play the game w/o the disk (only on multiplayer?). While I was playing one day some "clan" messed up my menu so I reinstalled and made the disk image again. Now the disk image doesnt work and it needs the disk to play. Is there something I'm doing wrong?