New machine boots fine as long as no USB HD's are connected, easy fix right? Well no..
So I went into the bios via F10 and eventually disabled the UEFI and made the HD the first boot under legacy.
Still no joy! Went back into bios and everything was still as I changed it.
Re-booted machine and instead of f10, used esc to bring up the boot menu. The boot menu indicated that everything was again on, in other words, the UEFI was not grayed out and the boot order was was as default setup would display.
Any thoughts? Does this regardless of front or rear USB ports used.