Well, this is what happened, believe it or not. Perhaps someone could explain how?
After many hours of moving things around and copying the Slackware64 files from the DVD to the hard drive, I made an ISO. The result was 72 gigs or so in size. While the ISO process was running I noticed the same directory name over and over again so I went through the directories one at a time until I came to the slackware64 directory.
There is suppose to be a text file in that directory labeled, "filelist.txt." Instead, I found a directory with that name. Inside that directory were all the folders and files from the parent directory slackware64 along with another copy of the directory "filelist.txt." Clicking on that revealed another "filelist.txt" directory, and another, and another, and another. It was duplicated 40 times.
Now all of this couldn't have fit on the DVD so somehow when one goes to copy the information to the hard drive there is some sort of error (or hack) that copies all those directories and their files FORTY times! Forty-one counting the parent directory.
I deleted all but the parent directory and the next ISO was 23 gigs which is still too big, so I went looking again and found a similar problem a folder with the name of "rawrite.exe" in the isolinux/sbootmgr directory. Again there were 40 copies.
The next ISO was 12 gigs so I went looking around again and found the same problem with /source/xap/vim-givm. I deleted those 40 copies of all the source directories and files and was finally able to make a 3.7 gig ISO.
Once made and burned to a DVD it booted up and the installation of Slackware64 went flawlessly and in record time. A full "everything, including the kitchen sink" install in 32 minutes flat.
So, again, does anyone know how something like this could happen. Oh, BTW, I checked the DVD and, yes, the duplicate directories are there, but that much data couldn't possibly fit on the DVD so how was it copied 40 times to the hard drive?