[javascript+HTML] preload?

hi guys I have a website…there’s a box that contain text and I use javascript to customize the scrollbar my question is sometimes when the page not load properly the box won’t display the whole content (confused…?let’s me just show you)

go to :
http://cg-animation.com/associates/nelson_dewey.html
and then scrolldown if everything seems okay then click on other employee then scrolldown to the bottom of the content and you’ll se what i means

plus if you use IE7 to load the page but before the loading process is complete you hover your cursor to the 3d btn then it won’t display a dropwon submenu instead it will display on top of the main menu until everything is load

my question is can a javascript do like a preloading in flash so it would make sure every elements are loading then display the page?