Submenu disapears before you can click it

Hi. If submenu direction is set to 'Up' then it disapear on hover and you can't click submenu item. You can check this behavior on my site zemanhdf.pl (item "Realizacje'). And if submenu direction is set "Down' then submenu items hide behind the slideshow locad directly under the menu. Would you solve both probles, please, because the site looks unproffesional with these bugs. Thanx in advance.