It has always worked for me by holding down the option key during boot but now it is not working. It just boots into mac os x without allowing me to choose the disk while I am holding option.

Any help?

Is your keyboard wired or wireless?

If it's wired, is it plugged directly into the back of the computer or in a hub?

instead of option key, try the ALT key, middle one of the three. Not the one with the apple logo, or control key.

instead of option key, try the ALT key, middle one of the three. Not the one with the apple logo, or control key.

Whoops sorry! Old XP user here, yes the Option and ALT keys are the same.

You have to hold the Alt/Option key when you hear the "tadaaa" from Mac. Hold it till you see an arrowhead show up.

If that doesn't work, maybe reboot with the mac DVD and go into repair mode?

Hi,

I am pretty sure it has to do with the computer detecting the keyboard on startup because no other key combinations (safe boot, single user, etc) work either.