I have a clean install of Windows 10 already activated and am having issues with my VPN. I therefore want to re-install Win 8.1 and still keep my Win 10 install, thus having a dual-boot configuration. I want to see if my VPN issue is caused by Win 10. No matter what version Win 8 iso (general, version specific) I use, no matter what Win 8 key I use (retail or public), I keep getting the same error when I boot from DVD and try to do a clean install of Win 8: "Windows cannot find the Microsoft Software License Terms. Make sure the installation sources are valid and restart the installation" Any ideas what is going on and how to fix it? Thanks!