NOTE: WinGX and Ortep for Windows NO LONGER need you to set any environment variables. Just install over your previous installation and after running the programs for the first time you can remove the WINGXDIR & ORTEPDIR environment variables from your list.
Newly compiled versions (23rd July 2023) of WinGX, Ortep & PWT are now available, which should have mutually compatible library files, plus some minor bug-fixes.