This is the only thing that worked for me in getting Paint Shop Pro 4.12 to work on Windows 10 Creators Edition.

1. Clicked Windows key +R.

2. Typed in regedit, and opened it.

3. In RegEdit.exe I went to HKEY_CURRENT_USER\Software\JASC.

a. Navigate to it by clicking the ">" before "HKEY_CURRENT_USER."

b. Then under that, the ">" before "Software."

c. Then the ">" before "JASC."

4. All those entries have to go.

5. So double click on "JASC."

6. Go to the "Edit" menu item on top.

7. Select "Delete"

8. In the "Confirm Key Delete" message that says "Are you sure you want to permanently delete this key and all of its subkeys?" click on the "Yes" button.

9. Close RegEdit and reboot your machine.

Now open your Paint Shop Pro and voilà it works!