coolmenu4 : alignement problem

Hi,

I have a display problem with cool menu4.
In fact, I have a menu that I have defined to be centered as my web site is centered in the browser.
My menu as a width of 800, the problem is when i resize my browser to a siez less than 800, my menu is not well display....I cannot see the left of the menu on about 20 pixels and I have a blank on the right on the same size....

Why? Do I have done something wrong or is there a bug in coolmenu display management?

Thanks, this is URGENT for my project!

Gaet