don't know ? I use Linux mint 17 mate. all I did was down load the iso with my windows 7 then burned a dvd then went to bios changed the boot order to optical drive first boot device with the Linux dvd in it and booted straight to Linux desktop ??
http://askubuntu.com/questions/329704/syslinux-no-default-or-ui-configuration-directive-found
did you copy the iso from the usb stick ? is the usb formatted correct ? may have a unsupported pendrive or defective ?
I would try another download of the iso and save it to a folder then burn it to a dvd ?
seems like I got it from University of Oklahoma last time ?? [ notice -- ''Media DVD '' ]
https://www.linuxmint.com/edition.php?id=206
you can insure a good download
https://community.linuxmint.com/tutorial/view/1987
I don't fool with the pen drive deal just not as ''goof proof '' as a live dvd way ?
you could try a slightly older mint 17 to see if something changes ?
[examples]
https://www.linuxmint.com/release.php?id=22
https://www.linuxmint.com/release.php?id=23
just to add maybe of interest ''But the same feature that blocks rootkits will also block other software, like Linux boot loaders ''
http://www.pcworld.com/article/2901262/microsoft-tightens-windows-10s-secure-boot-screws-where-does-that-leave-linux.html
between Microsoft and all there win-10 tricks and making it so proprietary and all the rest of the crap surrounding it then intel and how skylake ''works'' and all its limitations as well
to me anyone investing in any of those two thing just don't really realize how bad that are and how well there getting screwed over
a bad OS and a bad intel platform that's designed to only fully work together .as they see fit.. the more I see everyday on win -10 and skylake the more I see what I really got with win-7 and haswell , it works as I need it to not how ''they'' thing I need it to [opinion]
looks like intel is also making it to where you got to run 10 and I guess 10 only ?
http://arstechnica.com/information-technology/2016/01/skylake-users-given-18-months-to-upgrade-to-windows-10/
thing is I don't see or get how that may block a standalone Linux boot ? maybe disconnect the windows 10 hard drive so the only thing it can boot to is the Linux ?? just looks like a personal computer is a thing of the past ??