Weird: Category search drop down menu rolling down behind/below page
I am encountering an unusual behavior with my ClassiPress 3.1.9 category search drop down menu. When I click on the up/down arrows to unroll the menu, it seems to open up, but does not display on top. In IE, it becomes visible below the entire page, and in Firefox, it is not visible at all, however you can tell the menu is open because the roundness of the search bar outline is gone. Please take a look at the following ad page
and try to search for any phrase in different ad categories. Any suggestions to fix this would be greatly appreciated. Thanks in advance.