I formatted six USB flash drives with Rufus. Three are unbranded (2GB - $1.50 each), purchased when I was visiting an electronics flea market. The other three are the ubiquitous SanDisk Cruzer Glide (16GB). Rufus formats USB flash drives: https://www.majorgeeks.com/files/details/rufus.html Using the app PeToUSB, I installed BartPE on all six flash drives. The unbranded flash drives boot normally. The SanDisk drives will not boot. All six are new. If you are not familiar with PeToUSB read this: https://www.softpedia.com/get/System/Boot-Manager-Disk/PeToUSB.shtml The only difference between the unbranded (2GB) and SanDisk drives (16GB) is capacity. There is nothing on all six drives, except the BartPE folders and files. I hope a forum member can tell me why the SanDisk drives won't boot and how to fix the problem.