well wouldn't you know it! I found the answer myself just by accident of sorts. I can't believe after how many months of searching I end up figuring it out myself not long after posting here. Seems Firefox doesn't like a fixed page layout region. It shifts all the free standing text boxes down on the page which causes the overlapping effect. I discovered that if I take those text boxes and drop them into their own table everything displays perfectly in Firefox. So there it is!