FIREFOX not working but IE 8 is fine

I am having a problem with my images Not being shown on Firefox for the gallery/portfolio. It works perfectly for IE but not for Firefox. I am not sure what to do. I am using Pretty Photo (Jquery Lightbox)to display on my gallery page. The photos don’t work on Travel and Gallery Page. I know that I am displaying a lot photos but it should still work. Firefox cuts off the top row for some of the columns. The first group are ok but the rest lose the top row. Secondly the drop down menu acts up for both. Sometimes when I go to the drop down menu I can’t select an item when I go down with the pointer because the drop down menu goes back up. Has anyone else have had this issue? Lastly, firefox adds another tab with the name of all my pages under the slider for all the pages, and I don’t know why because IE doesn’t. Thank you for your time.