In CCleaner there's an option under the menu 'Registry' called 'Unused File Extension' which (if checked) lists all the filenames for which their extension isn't associated to any application. This should *only* apply to filenames and not to directories. If you have a directory with a dot (say 'test.xyz'), CCleaner will list it among unused file extensions (the unused file extension being 'xyz' of course).
You can test this. Make a directory (or a *folder* in the Microsoft Windows term) named 'test.xyz', access it (double-click the folder) and close it. Then run CClener with the option 'Unused File Extension' (in the menu 'Registry') checked. You'll see that this folder has been found by CCleaner as an unused file extension. All we did was just give the folder a dot in its name, but CCleaner assumed that the 'xyz' (in 'test.xyz') is an extension.
Please put a mechanism in CCleaner that would distinguish between files and directories. If CCleaner finds a directory, then the 'Unused File Extension' option should ignore it and not further deal with it.
