If I understand you correctly, you're saying that you are loading a menu file that resides on the network.
Then if a user launches AutoCAD and the network resource is not available (for whatever reason...), that the menu is not available.
Then if the user launches AutoCAD again, and the network resource IS available, the menu still does not load?
If this is correct so far, then what we do is to check to see if the menu is loaded using some autolisp code in "acad.lsp" and if not, it loads it.