XML problems?

I've put together a fairly simple XML parser that outputs embeded objects as a DOM. You can see that the XML files get parsed correctly (print "Open: $tag" etc for the proper functions..) and built the DOM correctly (print_r ( $this->dom ) at the last close_tag () call) but even after displaying the variable that holds the dom it for some reason resets that variable to the previous value ( example set $this->dom = 'goatpoo' ) as soon as it leaves that function although the other variables accessed all keep their proper values.. this happens even if i change the name of the dom variable. i checked and no where i can see does it rewrite that variable. i am using an object for the parsing xml_object() or whatever it's called sets it.. i was wondering if there might be a bug in PHP or am I just doing something wrong? I can supply my source if you like. Thanks.