After applying the Windows 10 update, and upon selecting a project to open, the file selection screen becomes cross hatched and a Run Time Error 75 appears.
The Error 75 occurs because Windows has deemed that you do not have ownership of the Hevacomp Projects folder. While this folder may not contain projects, it does contain control information for the software. As you don't have control of the folder, you cannot update it.
With these steps complete, you should have recreated the Hevacomp Projects folder, but with ownership assigned to your user account. The software should function correctly now.