Creation Kit, FO4 NG

UPDATE: SORTED. See reply for details.

Creation Kit, FO4 NG+, on PC, Win 10, all cleared through Anti-Virus, not on C: drive.

Has anyone got the CK to work? I downloaded the latest CK and it ran once. Now it doesn't start at all.

I've verified the files a few times, verified the game files. I'm getting no DMPs, no indications and not even a Windows Administration entry for the failure.

Any ideas folks might suggest I try, I'd truly appreciate it. Thanks!