I have a couple of different PE's already installed on my hard drive, and my BCD store, I'll try one of those, good idea. I'm not sure how effective that will be, though. I have more than one windows installation on my machine, and I tried from one of those, too, and didn't get anywhere. Maybe if the PE lacks support for NTFS file permissions, it might work.
I do have an old version, but what I think might be going on is that these are somehow flagged as mounted, somewhere, somehow. I do remember getting some kind of error, but I can't recall what it was, other than a dismount failure of some kind. I bet that's what locked up the temp files. It's been a while since I used it, now. I got all the drivers for all my hardware integrated, even my PCIe SSD card drivers into both the install.wim image, and the boot.wim PE image, so they recognize that. Maybe I should get the latest version, but I'm kind of finished, until some other reason to rebuild a windows installation source arises.
You wanna know what I did? I used it to pack a complete running and ready os, with everything installed and configured, into an install.wim, and it worked! I think it has to be on the same drive, so the windows disc signature matches, but it worked! Now it installs my old system as a fresh install. Well, old as in everything the way I like it with everything I need. Imagine your current os you are using now, as an installation source. I really didn't think that was going to fly at all. Well, you never know what you can do until you try, I suppose. That was something, and I'm not that easily impressed.