How do I boot from USB on a Mac? Mac OS X crashed on that PC and I want to make the owner switch to Ubuntu.
solution on the apple support site: http://support.apple.com/kb/HT1948
the gist of the answer is press the option key during boot and select the device....some devices have issues. there are troubleshooting steps at the website linked above
Just see the link below.. this might tell you Choose your device carefully https://help.ubuntu.com/community/MacBook