https://bbs.archlinux.org/viewtopic.php?id=69035You may need to remove easytag, I am not sure what other programs are using it.
As far as actually editing the entire menu, I don't believe that would be used particularly for places, however you can always just run the file manager specifically and navigate from there or even install another one, and through the menu edit, or panel edit, add the file manager there. TO Menu Edit, Right CLick on the Menu-->Edit Menus, and proceed, to edit the Panel, Right Click on the panel-->Add to Panel-->Custom Application Launcher, or Application Launcher,
So for example, I have Dolphin and I want to add a shortcut to my Panel, I will Right Click on the panel-->Application Launcher-->System Tools-->Dolphin-->Add
The File Manager on Mate is Caja, so for this it would be Custom Application Launcher