I've downloaded the latest SparkyLinux LXDE 86-64 image and DD'd into a USB stick. When I try to boot this, I get the error message,
presumably from the BIOS:
The system found unauthorised changes on the firmware, operating system or UEFI drivers.
Press [OK] to run the next boot device .....
I've checked the MD5 sum is OK. The machine will boot from a ubuntu-audio USB stick!
It's a new machine, ASUS Z170-K motherboard, with Intel i5 processor.