normal z-ordering and firefox

Hi, this is my first post and not long been using objectdock plus. Firstly, great app! however iv been having an annoying problem, iv got my main dock set to normal z-ordering, however when i select firefox from the dock, the dock wont dissapear unless i select another docklet and close that first. Im pretty sure it was fine when i 1st installed it. Oh yeah still using firefox 1.5 as was finding 2.0 a bit unstable. Any ideas???