https://www.dropbox.com/s/dr4e128y6y0xlw8/Fix1.zip?dl=0
While i can identify the freeze bug and fix it (try the quick-fix 3Dnes version above). I can not reproduce the corrupt 3dn file from the back-up one.
Could you pls try the new version with the back-up 3dn? If it still produces a corrupt 3dn with your new adjustment, pls report the exact steps to reproduce it.