Deleting a new, untitled folder without first renaming it (in column view) may inadvertently move the parent folder to the Trash under certain circumstances. This article applies to Mac OS X 10.2 through 10.3.9.
When you create a new folder, the name is immediately editable. If you move that folder to the the Trash via one of two specific methods before entering a name and the Finder window is in column view, then the parent folder will be moved to the Trash. (The parent folder is the one that contains the new folder.) This happens regardless of how you move the folder to the Trash. The two specific methods that result in this issue are: