Hi Bruce,
I am also using Windows 10 but unfortunately I am not getting the GPF on File/Open of a .bas file using x64 version of WinFBE.
Does it happen for you fore every *.bas file that you try to open, or just for a specific file? If just for one specific file then maybe it is the internal WinFBE parser that is GPF'ing when trying to parse the code for that file.
The author, David Roberts, mentioned the SetCompilerPathsII issue to me a few days ago. That tool is no longer applicable in WinFBE 3 so it has been removed from the distribution, however, an entry for it was still be generated for new default winfbe.ini configuration file.