Somehow it does because the menu works when BP isn’t activated. When it is activated, you aren’t logged in and you click on a page in the menu the only thing that happens is it adds “?bp_pc_redir_to=%2PAGE” to the hyperlink. And if I type http://www.example.com/PageName it also changes PageName to “?bp_pc_redir_to=%2PageName”.
Ther only plugin activated is BP. I changed the theme but it still doesn’t work : it adds “?bp_pc_redir_to=%2Factivities” to the hyperlink when clicking on the main menu if you’re not logged in. When you are logged it does work.