It's funny you should ask that...

I was coming back today to tell you of my blunder.

I have downloaded many copies of Zen Cart over the last few years. Always from this site. I've installed and customized them without problems so this was a very frustrating situation for me.

I started going backwards to see what (if any) differences there were between this install and any of the other 20+ I've done.

It turned out that I did an update on my SmartFTP program. I have used it for as long as I've been installing ZC. Errrrr. The program automatically switched from Auto Mode (which I set in preferences) to ASCII mode. Of course the original install worked well, no errors. But as I shut my computer down and came back to do customizations those files were uploaded incorrectly, causing more and more errors as I went. I've reported the problem to them and switched to the FireFTP program. Not as speedy as SmartFTP, but my blood pressure is lower. :)

There is a lesson to be learned here...

Thanks for all your help. You nailed it!