Drop menu layer issues

[reg44reg]

I have a horizontal drop menu at the top of my page thats working fine in FF, IE on PC but netscape (PC), FF and Safari on (mac) the second level menus fall/show behind a main content div just below it. Safari seems to be the worst off as it hides the entire dropped menu. Netscape wont even allow me to click on the second level, menu just closes.

Are there hacks to get the menu to open up above another div?

View page
http://asdi.robinjonesmarketing.com/subpage.htm

CSS Code
http://asdi.robinjonesmarketing.com/styles/asdimain.css