This option sets the case used for text in the directory and file windows. Mixed case is the case that was used to store the file name/directory when it was created. Lower case is selected with Mixed Case unchecked. A drive rescan must be performed to change the case of the directory tree following a change of this option.
This option does not affect the file name on disk. It simply forces the displayed file name to lower case. Use of this lower case option is discouraged but is provided for those users that prefer lower case.