After installed PCMan File Manager with LXDE, the gnome “places” menu items were opened by PCManFM as default. To switch back to nautilus, follow these steps:

1. check /usr/share/applications/nautilus-folder-hanlder.desktop
   make sure the line “Exec=nautilus” is not modified. (There are lots of hack article that teach user to change default file manager by modify this)
2. check /usr/share/applications/defaults.list
   grep the line “x-directory” by
   cat /usr/share/applications/defaults.list | grep x-directory
   make sure the value was kept as “nautilus-folder-handler.desktop”, if not, restore it.
   Then grep the line “inode” by
   cat /usr/share/applications/defaults.list | grep inode
   also be sure about the result “nautilus-folder-handler.desktop”. if not, restore it again.
3. So it must be your own configuration that has been changed. check ~/.local/share/applications/defaults.list
   grep the two lines described above, it must be changed to “pcmanfm-folder-handler.desktop”, so replace them by “nautilus-folder-handler.desktop”

To check the result, click menu item at once (no restart or logout needed), again, you see the slow file manager…