That IS strange. What version of Windows are you running?
EDIT: Wait a second, I think I see where the issue is. At first I thought your link from the 2.3.1 installer had a bad path to the map editor binary, as you listed C:\Program Files\* (which is in older versions of Windows) and not C:\Program Files (x86)\* (which is in more recent 64-bit Windows).
Now I just tried the 2.3.1 installer - either the NSIS script or the build system that created it has a bug: It places a "uforadiant" file in the right folder, but withOUT any extension. It should have an "exe" extension, as "uforadiant.exe", but the extension is missing.
IIRC the official installers from SourceForge were built with a cross-compile from Linux, if so this means the Linux cross-build script has a bug as it somehow drops or doesn't include the .exe extension.
I haven't played 2.3.x in a while, I forgot if Mattn or one of the other devs here built that specific installer, but I will check and report it.
In the meantime, try going to the folder the complete installer set up and rename "uforadiant" to "uforadiant.exe" and that should do the trick.