It could also be that these files have got corrupted in the download process. Can you try downloading them again ? You certainly should not have a problem downloading the one you paid for again as you will have proof of purchase.
It is a fairly rare occurrence, but I have had it happen once or twice.
thanks chris, I've deleted & re-downloaded these files multiple times & in the case of the software, the creator even sent me "his copy" with no restrictions --same result. I've tried various extraction software, opening the files before extraction, clicking 'open' instead of 'save' & I've scanned them with both avast & malwarebytes just for drill. As soon as I left-click the file for any action, I get the error message immediately & windows shuts down. yet I can open many other .zip files with no problem, also others can open the files I can't, downloaded from the same sources. seems I'm the only one having this issue --has to be something in my machine