Sticky Buttons!

Can anyone tell me why my movie clip buttons are so sticky!! Go to the management page here…

http://the1031solution.com/ten31_website/ten31Main.html

Notice when you run your mouse across them, they can get stuck on their OVER state.

I have this code in the main time line which I thought would stop the buttons sticking…

function over():Void {
this.over = true;
this.play();
}
function out():Void {
this.over = false;
this.play();
}

Is there anything else I can do to prevent this?

Thanks

Kit