Same thing happens to me to. It has to do with the frame the page is rendered in, (opening mobile facebook on a PSP portal in firefox has the same results). I've just clicking anywhere in the black brings back the home page. Hope this helps you.
i don't know if anybody else noticed yet... but facebook did some changes to the mobile version & now i get no black screen. that means no need to open in a new tab anymore if you don't want to.