Step taken:
- Took the USB Stick and saved the config colder
- Flashed the USB Stick with the USB-Creator
- Copied the config folder back onto it -> Same Error
- Removed the following files: "passwd", "secrets.tdb", "shadow", "smbpasswd"
- Restarted -> SMB Working
Then I just had to recreate the users. But the awesome thing was I only need to set the name and password. The exact permissions on the shares were retained in the share config. So it only took ~2 min to get all users back and now its happily chugging along.