And now S3D is crashing again when I try to modify FFF settings, looks like I get to re-do everything a third time
Also, I print off SD cards, so it has nothing to do with printing from USB in my case.
As others have also said, sadly one or more of your profiles is corrupt.
The best way I have found so far of identifying the corrupted profile(s), is to export each of them (sadly, one at a time!) to a directory of your choosing.
Any corrupt profiles will usually show up in that directory as being of being zero-bytes in size (or very close).
These MUST be deleted from S3D in order to get it to work reliably once again.
If you have particularly intricate and useful, but now corrupted profiles, that you cannot export - I recommend that you either write down the relevant values, or at least screen capture then to save later frustration.
If after you've exported all of the profiles (a backup is always handy after all) and deleted the damaged ones, if S3D still misbehaves, I'm afraid your only option currently is the Nuclear one - "Reset All Settings" in the Help menu.
I still find it hard to fathom why such an awesome program is so crippled by this massive piece of dumbness when it comes to profile management, and why there is no 'repair' facility.
If you do have to Nuke it, you *should* be OK to import the non-zero FFF profiles without incident. *SHOULD!*
Hope this helps you.