At some point when I was busy trying to figure out how to install CursorXP trails to CursorFX; which TPScroggins help me with on my "How to install trails in CursorFX" thread, Configure CursorFX had stopped working completely.
The good news though, is that it turned out that the 'VLC Media Player' was interfering with the CursorFX Configuration. It wasn't too difficult to tell this was the case after opening Windows Explorer and clicking directly on the executable file and the VLC Media Player opened instead. So of course I uninstalled it and restarted my PC. Now it's working perfectly again.
So if you are here today on the forums for help with CursorFX Configuration no longer working, just do what I did. Go to the main Windows Explorer install location at 'C:\Program Files (x86)\Stardock\CursorFX', and click directly on the main CursorFXConfig.exe, and see if another program opens instead.