Reported from user josh and reproduced with version 4.0.36 (xampp on windows):
If you have a catagory with a / in ie AC/DC it creates a folder AC, and then folder DC in AC.
Edit:
Will be fixed in one of the next versions!
Edit:
After further checking and using the various options in the Files and Folders tab, the problem only exchanges when the Unicode option is not active. As this is not an active default after installation, I have added another short check. So it is fixed in version 4.0.37.