Solved HP Laptop W8.1 will not Boot from DVD

[BuckSkin]

My first post here; I hope it is in the right place.
I have been fighting with an HP Pavilion laptop with W8.1 for hours, trying to get it to boot to an install DVD
I have used the same DVD on numerous machines and it has never failed.
No matter what I do, I get a message "Selected Boot Image did not Authenticate"
I went into BIOS and made certain boot from DVD is enabled.
I moved DVD to the top of the boot list.
I have searched and read and reread articles and followed any instructions that seemed to pertain and I am about at my wits end with this mess.
Can someone please tell me how to get this machine to boot from a disk ?

Thanks for reading and all help is appreciated.

 

[BuckSkin]

I found this; --- BUT, there is obviously a very important step that has been left out or some missing information.

HP Notebook PCs - Cannot Start Notebook Computer From a Bootable CD or DVD | HP® Customer Support

How do I get from Step 2 to Step 3 ?

I can get the black menu, but I don't know what to do to proceed to the blue menu.

 

[BuckSkin]

I had to skin the cat in a different direction, but I finally managed to get in there.
Nothing about this machine works like explained in all of the tutorials.

 

[BuckSkin]

More Problems:
What I am trying to do: (I have successfully done this several times on other machines)
I have created a partition for Windows 7 Pro alongside the already installed Windows 8.1
I have finally got it to boot from the disk; however, it gets past the "loading files" and seems to hang at the "Starting Windows".
It completely creates the 4-colored logo and everything is clear and sharp; it just stays there.
Am I just in too big of a hurry, or will I wait until doomsday and get no further ?

 

[BuckSkin]

I may have a better solution to this dilemma; seeing as, once Windows 7 is installed, it will probably never be booted into W8.1 ever again for the rest of time, what would be the outcome if I did enable Legacy Support, went ahead with my W7 install, and if, for whatever unfathomable reason I ever had need for W8.1, it would be a simple matter in W7 to access the System Configuration and simply disable Legacy Support.

Are there any holes in that plan ?

Thanks.

 

[JustHarry]

In the BIOS you have enabled legacy mode?

 

[BuckSkin]

I have not done anything else yet; I was just looking for a solution before I got in too deep.