Try downloading again, happens sometimes during the download. They are for sure not corrupt
I felt really silly posting this message, but I have been able to verify that there is nothing wrong with the download ZIP file. For some reason my PC at work cannot unzip that file, but all my other computers at home unzip it just fine.
Looks like a trouble ticket for tech support here at work. :)
Thanks for the reassurance. And now I know I'm not bonkers...
happens to all of us one day or another :-)