OK, moving the preferences to a different folder with the last step you detailed does nothing. I still get the exact same error when I try to save.
I also went into the Preferences file and changed all the instances where it points to the backup_prefs.txt, still same result :/
I will try and uninstall all versions of Wings now and just install the latest one. See what happens.
EDIT:
OK, I have no clue what happened, but I tried to delete the materials in the wings file (which were not used anyway) and that resulted in not bringing up the save problems anymore in the same file. I got some more to go through, will see if the problems come up in those as well and if they go away if I delete the materials. Very odd.
I also went into the Preferences file and changed all the instances where it points to the backup_prefs.txt, still same result :/
I will try and uninstall all versions of Wings now and just install the latest one. See what happens.
EDIT:
OK, I have no clue what happened, but I tried to delete the materials in the wings file (which were not used anyway) and that resulted in not bringing up the save problems anymore in the same file. I got some more to go through, will see if the problems come up in those as well and if they go away if I delete the materials. Very odd.