Sound on mouseover loses Down and OverDown rollover states??

I tried to include sound on a mouseover of my web's nav buttons. The buttons
have 4 rollover states. However, when I include the sound on mouseover, I
lose the buttonDown and Mouseoverdown states for my Nav buttons. AT
www.bridgemate.net you can see the problem. I've put the sound on the Home
and Features pages, but not on the other pages.

Anyone know what the problem is? It looks like I can have sound OR 4
rollover states. Of course I want it all