On my website http://www.mvl.eu I used superfish for a submenu. The submenu IS visible (z-index problem), but is is not clickable, because it disappears if you move to the sublinks. This problem only happens in IE9, until IE8 there was no problem. Can someone please tell me what the problem is, because i'm pretty out of ideas. Thanx!
Having just checked your website, I can confirm this is also an issue on IE7, unless you move the mouse down fast enough. Looks like there is some kind of gap between the definition of the menu title, and the menu items. Perhaps the issue is when the mouse is in this gap?