
Its that 'legacy optical boot' being automatically disabled is what is probably causing your problems. The systems are designed to be reverse compatible with old boot disks, which makes 'converting the Cd to EUFI' irrelevant.
HIREN BOOT CD ISO 10.5 WINDOWS
The OEM Windows has to be booted, and the drive order enabled and changed from there! That presents a mess of catch-22. Some Toshiba's dont' even give the option to change that in the bios. Because, what I usually find (and why I use the USB) is that many systems come with the boot-to-optical drive disabled. If you are looking for a read only copy (CD/DVD), there are tools that can make a EUFI bootable CD and then copy the files over. I made one following this: It boots on my new system and works on all the computers I get in for repairs. CONFIG_EFI=y CONFIG_RELOCATABLE=y CONFIG_EFI_PARTITION=y CONFIG_EFI_VARS=y CONFIG_FB_EFI=y Hiren's kernel is not built with those flags 'ON' and you (surely) do not have the exact sources/config for re-building the kernel while adding the above mentioned missing EFI related parameters.

By UEFI enabled ISO's I mean that the ISO files contain a BOOT EFI directory with a EFI bootloader. A EFI computer (SecureBoot disabled) Edit 2: There are many suggestion to use tools which make an ISO bootable with UEFI on a flash disk, however it's not that easy as you can only do that with UEFI-enabled ISO's.

To clarify before accepting an answer: I will test the solution on: ComboFix (): Designed to cleanup malware infections and restore settings modified by malware. Hiren’s Boot CD 11.0 ISO contains a lot of testing and troubleshooting tools. I am a long term user of, but the CD does not support booting on UEFI/EFI/SecureBoot hardware, is there some kind of update/patch to apply to the cd image to be able to boot without BIOS? Can I make this myself? (By putting some files in the iso image?) Edit: Running Hiren from USB on EFI counts too as an alternative.
