A couple of problems

ok, I´m doing my website and I have 4 buttons, each one when you press it loads an external swf, my problem is that when i press a button no problem, the swf loads, but when I press another button the SWF loads on top of the other SWF, and looks terrible, what should I do?? here´s the code I´m using:

loadMovie(“mis.swf”, _root.container);