OpenXR Developer Tools Crash to Desktop when started

I have a problem and am hoping someone can help.
A month ago I installed OpenXR Development Tools and everything worked fine. I was able to use it normally.
About a week ago, after having done some moving of apps in my steam library, I opened it and it now starts and shows the main screen and then immediately exits with no explanation.
Thinking that my moving of files had caused the problem I uninstalled it and reinstalled it but it still fails the same way. I think that there are still some option files or some such which don’t get deleted when it is uninstalled.
It is very frustrating because I have found it to be a vital piece of software running VR.
I have another PC and it always works perfectly on that machine.
I need to find a way to completely remove it but I can’t find out where it is installed and where it keeps it’s options, settings etc.

Can anyone help please.?