I ultimately threw away the idea of running Ubuntu from a USB drive, bought a cheap SSD and installed it on that. Runs like a charm! The problem seems to be universal with modern, UEFI BIOS computers. There's a lot of massaging that needs to be done (not worth the effort) to get things to work. In any case, with a native installation on a SATA SSD, the machine flies! Oh, how far Linux has come over the years! Just great.
I am trying to boot Ubuntu from a USB drive and - while the boot menu on my Inspiron 3668 shows that I have a USB drive - I keep getting a "no grub" error. Does anyone know how to boot Linux from a USB drive on my machine. It works just fine on other, older PCs I've used, but it won't work on this [NAME] machine.
Booting Ubuntu from a USB Drive