Problem: Somewhere in the file system of a mounted SMB share, a folder is shown twice. They have the same name, but case is different (e.g., Folder_One and FOLDER_ONE). On the actual file system, only one exists (most likely Folder_One). Found w/ OS X 10.4.11 and Samba 3.0.26a.
Fix: Delete the .DS_Store file inside the parent folder, parallel to the folder itself.