This is most likely because you have deleted a file in DOS that references a long file name in Windows. DOS does not support long file names. You can define a long file name as any file name with more than eight characters or any file extension with more than three characters. If DOS encounters a long file name, it will rename it to support the DOS filename standard. This means DOS will keep the first seven characters of the filename and append a tilde ( ~ ) symbol at the end to indicate the filename has been truncated so that DOS can read it.

When DOS truncates a file in this way, it essentially breaks the file up into multiple pointers that allow Windows to recognize the file even if the filename has been truncated. If you delete the file in Windows, it will recognize the file and all of its pointers as a single file. However, if you attempt to delete a file with a truncated file name in DOS, it will only recognize the file itself and ignore the filename pointers, leaving them in the directory. This will prevent you from deleting the directory in DOS and the filename pointers are inaccessible in Windows.

If you need to delete a file with a truncated filename on the Multipurpose USB Device, delete the file from within Windows. If you have already deleted files in DOS with truncated filenames and need to restore the directory structure, use the Multipurpose USB Device Restore Tool to restore it to its original configuration. For more information on the Multipurpose USB Device Restore Tool, SEE ALSO "Install Options Menu" on page 12.