Jerome,
I downloaded SpaceSniffer to test this on my system to see what may be wrong. I see that SpaceSniffer does not "Run as administrator" (elevated) by default when you run it, so a standard user should be able to run SpaceSniffer without having to use this tutorial to do so.
If you manually set the SpaceSniffer.exe file to
Run this program as an administrator in
compatibility mode, then that would be why you are getting this error. You would need to uncheck the
Run this program as an administrator box so that the standard user will be able to run it without using this tutorial instead.
This is why you are having this issue since it's not natively running elevated, and you manually set it to.
Hope this sorts it for you.