T7910 USB Boot Problem

I'm having a really hard time booting from a Windows PE USB stick, in order to restore a Windows 10 (64 bit) system image. I have tried both Legacy, as well as UEFI boot, but 99% of the time I get an "Invalid Partition Table!" error message.

I did succeed once, an hour or so ago, but can't retrace my steps again. I do not remember what I did. My BIOS version is A32, which is the most up to date. The whole process seems very hit and miss.....mostly miss!  Any suggestions?