Thanks for that. Very interesting.
So I put one of those disks in the tray, and I selected the option you recommended. I then right-clicked on the file pmagic_2013_08_01.iso, and chose "Burn disk image". The machine seemed to do as one would hope. It apparently burned the file to the disk, "finalized" it, then checked it, finding it to be OK. Then it ejected the disk.
So I turned off the computer, reinserted the disk in the tray and pushed it in, and started the computer. While it was starting, I pressed F9 repeatedly until I got to a menu that offered me a choice of boot devices. I chose the DVD drive. The response given was, "Selected boot image did not authenticate."
I then chose the C drive and booted normally. Looking at the contents of the disk I burned, I see this:
BTW, do you know how I can remove those last two files from the queue of files to be burned to disk?