Insert boot device problem?

on some systems, simply setting the boot order doesnt do it ....... some of them in order to boot off cd rom, (even though you have it set for first boot in bios) you still have to enter a boot menu and tell it what drive to boot from if any other than the hdd. for exampl my asus ...... on startup while still on the acer screen, keep tapping f8 , and on my compaq same thing but tapping escape instead .... a menu will pop up and tell me to select drive to boot from. cant say what to tap exactly on your system. try escape, or delete you diffrent f keys --- most probly f10 or 12 .... also look close at your boot screen when you turn your system on, it will normaly tell what to pres to enter boot menu