Q-Dir 7.12 only works in x86 mode irrespective of the operating system (x64 or x86), whereas it has both versions viz.x64 and x86 and should execute the particular file depending upon the OS.

I was able to manually fix it by going to the x64 folder and rename Q-Dir_x64.exe to Q-Dir.exe.

N.B. (for Admin) : Please rename the Q-Dir_x64.exe file to Q-Dir.exe and fix the installer.