ENTITY GIVES ME ERROR PLZ HELP!!!!!!!!

[motoman32002]

ENTITY** when i select a map and click on the blue+ then view BSP error comes up saying "main menu-map not found" then another message comes up saying unhandled exception has occured in your application. I can click details,continue,or quit also it says (object reference not set to an instance of an objets) please help im trying to make a warthog map and really need help thanks my email is motoman32002@yahoo.com

[SpecOp44]

Make sure Mainmenu.map is in the same directory as the map you are trying to view.