CSS navbar dropdowns behind javascript slideshow

[iLLfLiP]

Hi, I am currently having trouble with my drop down nav.
The drop down nav works fine; however I decided to put a javascript slideshow underneath the nav bar, which now causes problems with the drop downs.

For some reason, the drop downs now appear behind the javascript slideshow.
Is there some sort of CSS hack that will easily allow the nav bar drop downs to appear over the javascript slideshow instead of behind it?
It seems to work fine in IE, but I can't seem to get it to work in Firefox...

thanks in advance for any help

[iLLfLiP]

here is part of the code as well:

.yuimenubar{visibility:visible;position:static;}
.yuimenu .yuimenu,.yuimenubar .yuimenu{visibility:hidden;position:absolute; top:-10000px;left:-10000px;}
.yuimenuitemlabel,.yuimenubaritemlabel{text-align:left;white-space:nowrap;}
.yui-menu-shadow{position:absolute;visibility:hidden;}
.topnavigation ul li.yuimenuitem a span {position:fixed;width:180px;height:auto;background-color:#4a95d9; text-transform:capitalize;font-weight:normal;font-size:1em;text-align:left; margin:0 0 0 -15px;}

[MorganA]

You may want to try playing with z-index values. I believe this only works on items with absolute positioning. But z-index: 1; should send an item to front, z-index: -1 sends it to back.

[iLLfLiP]

thanks for the suggestion Morgan.
I actually tried that previously, but still no go. The drop downs are still always dropping behind the javascript slideshow.

Is there a particular line or area I should try adding the z-index values to?

Thanks