Disk drive spinning with no disk in?

Are you sure the disk is spinning all during the game? It's normal for it to spin up when you launch, it does a disk check to validate that the disk is in the drive. After that though, it shouldn't be spinning your disk.

If the disk drive makes an increesed buzzing noise (Louder than normal) while the disk is spinning, You may have an unbalanced disk. Which means when it spins up to read the disk will be vibrating inside the drive making it unreadable.

This could also explain why the disk can read some times but not all the time, due to the faster the disk spins the worse the problem will be.

When you put your disk in can you hear your disk drive spin up or does it not even recognize that there is a disk in it ?

Yes you do. But the disk won't spin. Keeps your disk drive from wearing out.

Do you have the disk in the drive? Even though a game is downloaded to the hard drive, you still have to have the disk in the drive in order to launch it. The system will spin the disk for a second to verify that it is there, and then everything afterwards
will run from the hard drive.