Help!: Problem when trying to replace Windows Explorer

[HackerTradition]

I'm using TC UP 5.6 on Windows 7, and I want that when I double click a folder, it opens in TC rather than Windows Explorer.
So I clicked Appearance > Replace Windows Explorer > On, then popped up a message box saying "file not found".

see: http://www.flickr.com/photos/74626162@N0...hotostream
and
http://www.flickr.com/photos/74626162@N0...otostream/

I have read the help documentation and googled but didn't manage to find an answer~~ Any idea? Thanks a lot!