I've been struggling with this new HP Envy 700-216 computer since 18 Feb trying to install LMDE alongside Windows 8.1. I finally found one answer I believe worth sharing with you. It is a free Boot Loader for Multiple OS's on one computer. It is ReFInd and available from http://www.rodsbooks.com/refind/. It is a simple download and works. Hope this is a helpful hint.