Menu not working in IE

I have a development site at arrowengine.com/dev. The Maximenu is in the left side column and it works fine in Firefox but the menu does not fly out in IE. Also there is extra space under the item that has sub menus in IE.

J'ai un site de développement à arrowengine.com / dev. Le Maximenu est dans la colonne de gauche et il fonctionne très bien dans Firefox, mais le menu ne vole pas dans IE. Il ya aussi un espace supplémentaire au titre du point qui a sous-menus dans IE.

Hi
your module dropdownmegamenu creates a JS error. Please unpublish it, see if maximenu works and tell me. I'll have a look again
Ced

I disabled the dropdownmegamenu and the Vertical maximenu still has the same problems that it did before.

please let it deactivated so that I can see

It is deactivated now. Thank you!

it seems to be working now on IE8, but there is a css (?) issue in IE9