Navigation shining through my SWF

I realize that this issue is probably partly the fault of the 3rd party that is serving my SWF, and a site whose CSS I have no say over, but I am trying to think of a work around.

Inititially we were using Pointroll to serve two JPG images, one of which appears for 3 seconds and retracts. A recent CSS change to the sites navigation has caused the navigation to shine though in Firefox. Using SWFs and publishing as opague has not solved the issue. The navigation is shining through the bitmap in the SWF.

The navigation’s CSS is

div#main-menu {	width: 970px;	height: 51px;	z-index: 99999999;	position:relative;}

Another obtion would be to put the JPG in a div with an inline z-index style, and book it as custom HTML. BUt before I try that route is it even possible to get above 99999999?