Volume shows (as start-up disk) but won't boot!

[dee dee]

Hi folks,

I'm trying to simply create a bootable disk using my external hard drive.

I've used Superduper to create a backup (all files) onto my external hard drive: which has 2 partitions, both Mac OS Extended (Journaled).

In System Prefs, Startup Disk - shows the same folder name (Mac OSX, 10.4.11, on Macintosh HD) on both my internal drive AND external drive...

I've tried to choose the external drive (in System Prefs->Startup Disk) and press the restart button... no luck.
I've tried holding down the "option" key at startup... no luck.

Any ideas why I can't startup off the external hard drive despite it "being a valid boot disk"?

I've scoured the net, these forums... apple, the Superduper support/help/faqs...

I'm running OSX 10.4.11

Thanks in advance folks...

D

 

[brijazz]

Is your disk formatted using the "GUID Partition Table"? That's necessary for your disk to be bootable, I believe. You can check in Disk Utility.

 

[dee dee]

Is your disk formatted using the "GUID Partition Table"? That's necessary for your disk to be bootable, I believe. You can check in Disk Utility.

Yes. thanks so much for the reply.

Anyone else with any clues to this seemingly straightforward dilemma?