Can't Boot From Bootable CD -- Bios Set Correctly

I am trying for the first time to boot my Windows 8.1 laptop from the internal CD-DVD drive. I have a bootable CD in there, and yes, I do have the bios set with CDROM drive as first in the list to boot from. But when I try to boot from the CD, it won't boot, instead the computer gives me this message:

"ATAPI CDROM has been blocked by the current security policy."

(Its actually a DVD drive.) All it lets me do at that message is hit the Enter key to OK the message, and then it boots from the hard drive.

I have no idea where "security policy" settings are or what they are set for. What do I have to do to get this to boot?

This is a Gateway laptop, 2.2 MHz Intel Pentium processor, 4 GB RAM, 64 bit OS, with Windows 8.1 fully updated, and Windows Defender running and fully updated.

I have already looked everywhere I can find, but nothing seems to address this message or issue, as follows:

*I went to Help menu to look up "Security Policy." While the computer is giving me the message about "security policy," the Help menu has no idea what "security policy" is, it just comes up blank!

*I went to Control Panels/System and Security/Action Center/Change Windows Settings/Smart Screen/... All I found in there that might be involved is a setting to block anything downloaded from the Internet until I give administrator access. Well, the booting issue didn't allow me to give administrator access (yes, I am the administrator) when I tried to boot, I only could hit the enter key to OK. Nonetheless, I changed to: notify me but proceed (not a quote).

With that, I tried again, but it still would not boot from the CD, got the same message, so that setting is not it. I changed the setting back.

I see no other setting there that could be related by even a stretch. And the control panels should be dealing with the OS anyway, and this is happening while trying to boot from the OS on the CD, not the hard drive. That is, this is something in the root.

*I then went into bios area (UEFI Firmware) by sweeping in from the right and into Settings/Change PC settings ..., and found a tab in bios for Security. Looking there, there is a list of things, but it lets me access only "Supervisor Password." It was currently set as "clear," meaning no password. I left it as that -- surely I can't need a password just to boot from a CD, and the message I got in trying to boot from the CD did not allow me to enter a password.

Other settings in the Security tab were not accessible. The only ones they included that might be remotely related were:

*Password on Boot, which was set as no password. But again, the message I get with this issue does not ask for nor allow me to enter a password.

*Secure Boot Mode: Standard (It does not let me access to change that.)

Some others also were in the list that are not worth listing, not even vaguely related.

I then went into some other things elsewhere in the main settings called Startup Settings. The only thing in there that sounded the least bit vaguely related was "Enable boot logging." I punched F2 to go into that, but the machine instead restarted, and did not start from the CDROM, same message again. I went back to it, and it is still listed as Enable boot logging, does not instead say Disable - so I don't know if anything even got changed. I did not touch it again, left it as-is.

So, that's it. I've checked all the settings I know about. Nothing about this bit about "ATAPI CDROM has been blocked by current security policy."

I tested with two DVDs that I have booted from in the past on other Windows machines -- they also would not boot, but they did not give me that message.

I note, all three CDs/DVDs are being read fine by the DVD drive once the machine is booted in Windows 8.1 from the hard drive - so the issue is not that the DVD drive can't read the disks.

Where is this "security policy" set?! What do I need to do to get this to boot from the CD?