Chrome 45 has a current glitch that will incorrectly display the WordPress admin menu. It is a discrepancy on the height of WordPress versus the height of the screen used.

If you use chrome to manage your WordPress site, then please go to your functions.php file located here:

http://www.yourwebsitename.com/wp-admin/theme-editor.php?file=functions.php&theme=yourtheme

and add this code to the end of your funtions.php file:

function admin_menu_fix() {
echo ‘<style>
#adminmenu { transform: translateZ(0); }
</style>’;
}
add_action(‘admin_head’, ‘admin_menu_fix’);

Read More: http://wptavern.com/a-bug-in-chrome-45-causes-wordpress-admin-menu-to-break