I have created a startup disk on USB thumb drive for an ancient desktop. I never tried to boot it up. Nowadays, basically it's a full copy of virgin OS on flash drive. For this reason you shouldn't bother with Windows recovery. Have Ubuntu dual boot and you can read and write your drives no matter what. A flash drive is extra protection when both boot fails. A 2 GB drive is too cheap for the postage. If you have Frys or Micro Centers, you can pick it up dirt cheap.
For strange reasons the flash drive wouldn't boot. I searched the Web. All the problems and solutions are not relevant to me. There's only one person saying that must be memory. Of course, but memory errors are the most spectacular. I'm not having anything spectacular. As a last resort I tested my memory using the memtest that comes with Ubuntu.
It wasn't surprising that I have at least a memory error. I think I spotted errors long ago. I don't believe it because it passed the BIOS tests, and Windows and Ubuntu boots well.
For no good reason I swapped the memory banks. It was scary as the motherboard refuse to boot again. It boots if I swap them back. So the simple memory tests test only some of the bytes, not all the bytes.
So I went to Micro Center to pick up some cheap memory. Memtest shows no error and everything boots, including the USB flash drive. Amen.
The life time guarantee on the memory is basically useless. By the time good memory fail, it will be obsolete, if not, dirt cheap. If you are still using your obsolete system, for memory you cannot wait for the return authorization and wait for them to sent you the memory. And if you bother to pull out the memory, it's worth while to upgrade to bigger memories.
There comes a time when obsolete parts cost more than new parts, for the hard to find factor. Basically this is driving you to give up your obsolete system and upgrade.