This is generally caused by CSS rule that gives submenus a constant width. To remove that constant width of submenus, simply put following code in your Custom CSS area in the options page:
[css]ul.dropdown ul { width: auto !important; }[/css]

Part of submenus not visible

The container element may have overflow:hidden in CSS code. This cuts overflowing elements and they are only partly visible. Try removing overflow attribute from the container element.

Sub lists can be seen in the source code of the page, but dropdown menu doesn’t work

This is generally caused by themes changing jquery code. Try disabling effects, if that works it means your jquery version is changed by your theme. If it still doesn’t work you need a wp_footer call in your footer.php file.

You are probably using Custom menus. For custom menus you have to add “Home” item from Pages in the WordPress “Menus” page. Plugin doesn’t add any custom links (home/admin/register) to the menu for Custom Menus.

If you are using a wordpress menu you have to add it to your menu yourself.

How can i sort / change order of items in my menu?

You can only do this if you are using Appearance->Menus to define your menus. Automatically generated menus (Categories and Pages) can not be sorted.

Your problems not solved?

Issue your problem here with URL of the site. And I will add the solution.