Play With Ubuntu, Now Mac Won't Boot!

[kentborg-KwkGvOEf1og at public.gmane.org (Kent Borg)]

I can't get my (wife's!) Macbook Pro (old model 17") to boot from its
internal hard disk. 

I was playing with Ubuntu on an external USB hard disk...

I installed both Mac OS X and Ubuntu 9.04 on the external disk.  The Mac
OS installation boots fine, the Ubuntu installation does not (I am
guessing I needed to use Bootcamp and I didn't).

Now I can boot from the external disk and I can boot from a CD but I
CANNOT boot from the internal disk. 

 - When I am booted from the external disk all the internal disk files
seem to be there, the Disk Utility was happy with a disk check.

 - I tried to set the internal disk as the boot disk using the Disk
Utility (it thinks that is a reasonable option), but that doesn't work.

 - I tried to boot with the option key down (to get list of boot
options), all I get is a mouse pointer (or external disk if external is
plugged in).

 - I tried to boot with the D-key held down to force booting from the
internal disk, but that doesn't work.

 - I reset the parameter RAM (cmd-option-P-R when booting).

 - I reset the power manager unit (pull battery and power, hold down
power button for 5-seconds).

My guess is that the either Ubuntu or Mac OS installer flipped some
obscure but crucial bit in the partitioning, something the Disk Utility
doesn't notice but the EFI bootrom does care about.  Suggestions??


Thanks,

-kb, the Kent who is currently doing a complete "rsync -ax" from the
internal to the external disk, in case he needs to reinstall everything
just to get the partitioning correct again.