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So I expanded a bootable .iso image of openSUSEx64 11.3 onto my 16GB USB thumb drive following the steps i found on a web site .

When i restarted the macbook with the option key pressed, the USB drive did not appear.

Can you guys please help me figure out why the USB drive's not being recognized at boot-up ?

Here is the web site i used (option 4) :

http://www.webupd8.org/2009/04/4-ways-to-create-bootable-live-usb.html

Are you sure the USB drive is bootable (tried it in another computer)?
 
Yes, windows cannot boot from thumbdrive easily.

However, I was able to boot linux from a standard thumbdrive.

You probably didn't instal it correctly.
 
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