Error 1935 - can't install programs on Win7/64/i7 machine

I can no longer install any programs on my Win7/64 PC. Each time I try, I get an error message 1935 as seen in the attachment below. Programs I've tried to install include Dragon Naturally Speaking 11.5 (the first one to get the 1935 error), Office 2010 starter edition and LibreOffice. All provide the same error. The attached message came from an Office 2010 attempt. I have tried: *...