Not very elegant solutions but here is what I do whenever I don't have a choice other than IE
Left click and hold (i.e. don't release the left mouse button) on the main menu item, move the pointer down the menu selections (as if you were trying to drag the main menu item) and then release the mouse button. Now the drop list should stick and you should be able to make a selection by clicking on it.
Right click on the main menu. Move the pointer to the droplist area and hit the escape key or simply click on the selection if you can partially see it.
Left click main menu then move the cursur swiftly from the main menu item over to the drop list.