Toshiba Notebooks — Disable Fast Boot
Some Toshiba notebook models provide an option in the BIOS (Setup) for Boot Speed: Fast. This option causes the system to only boot from the internal hard disk, and disables the startup functions such as F2 (Setup) and F12 (Boot Media). By default the Boot Speed is Normal.
If you are unable to boot from a CD/DVD on a Toshiba laptop, or access the BIOS setup functions, this may be the reason.
To bypass Fast mode, turn the machine off. Then hold down F12 and power the machine on. Keep holding down F12 until you see the screen display show the options for F2 and F12. Then you can choose a boot option or enter Setup.
Also see http://forums.toshiba.com/t5/Windows-8-8-1-Knowledge-Base/How-To-Enter-the-system-BIOS-or-UEFI-on-Windows-8-1-or-Windows-8/ta-p/329292.