Macintosh HD boot drive doesn't show up as Startup Disk (but boots fine)?!?

Hi,

My main internal bootable disk (Macintosh HD) does not show up in Systems Preferences > Startup Disk. If I want to boot from it, I have to either hold down the "Option" key at startup (and the disk appears fine, so I select it), or I have to wait for the machine to explore all other boot options before it finally resorts to booting from the internal Macintosh HD.

I cannot simply select "Macintosh HD" from the Startup Disk preference pane.

I have already tried repairing permissions, and I did a "Verify" in Disk Utility - everything checks out fine.

I even replaced the StartupDisk.prefpane file from another disk, but no improvement.

How can I get my hard drive to show up in the "Startup Disk" preferences?

(I should mention that this is a new hard drive that I just installed by cloning it from another bootable drive). The other bootable drive shows up fine in the Startup Disk prefs.

Help would be greatly appreciated!