Create Gallery / Images (Error 404)

When I access the Gallery menus from the WordPress Dashboard, and click on options “Add Gallery / Images”, “Tags”, “Options”, “Style”, “Role” the page always looks like its just about to load that sections, and sometimes I even almost see the options in that section I click on, then all the sudden it flashes and goes to the default error 404 page that word press creates. Nothing has really changes from what I can tell, WordPress is current, as well as this plugin. haven’t added any recent plugins. I haven’t tried deactivating everything yet and will be doing so tonight to see if that helps at all. any help would be great! thanks

http://wordpress.org/extend/plugins/nextgen-gallery/