Registered File Type Hijacked

How to restore the default action for File Type (Folder & File Folder). 2 PCs under my supervision have this problem:-

When a folder is doubleclicked in either Windows Explorer or My Documents, the folder will be open by ACDSee. I uninstalled the program and then it open in a separate window instead. I’ve adjust the Folder Option to “Open each folder in the same window” but it doesn’t work. The default action for this can’t be edited in File Type option. I’ve tried to create a new default action for it:- Open with EXPLORER.EXE; it doesn’t work either.

Those PCs operated under Win XP Pro. All recent patches and updates are applied accordingly.

Is there any workaround to restore the default action for the file type (Folder & File Folder) to open in the same window?