Whew! Read through the entire thread up to this point and am impressed with the dedicated help @RobH2 has been getting.
The one thing that sticks out in my mind is that OP asserts they did a clean install some time back yet the system disk partition layout I'm seeing posted seems odd based on evderything I've read up until now.
As Steve and Mike just pointed out, the boot as directed from BIOS and the system disk partition scheme should be consistent: if booting UEFI, system disk should be GPT - if booting legacy, system disk should be MBR.
From a post by @topgundcp :
Yes, as Dude just posted, there are ways around doing a clean install and surgery on the partitions can be performed to get legacy/MBR or UEFI/GPT arranged.
- 500MB System Reserved partition
- C: Drive
- 450MB recovery partition
- 100MB EFI System Partition
- 16MB MSR partition
- C drive.
It's just that the "clean install" assertion sticks with me and (aside from all other potential problems discussed), it begs the question of me:
Rob, are you so invested in the programs already installed on the system disk that you wouldn't entertain doing a truly clean install of Win10 again to get your BIOS and disk scheme lined up as Microsoft would do it by default?