Weird problem with MC visibility

I have a flash application where i use toggling the visibility of some MCs to create an effect of menus. It works fine until i revisit the initial frame to reenter parameters. Then on some cases the visibility doesnt turn off. Instead the MC is still visible but if i trace its visibility it says false even if its visible!! But if i show another menu and then close both menus in works. I have no idea what could be the problem. Can anyone help me?
The url is http://bine.homeftp.net/kemont/glavno.html if you want to see for yourself. Just enter 2500 in boxes marked with an * and then try clicking the buttons. The bottom left one is to reenter parameters. The big bottom right is to send an inquiry - dont click that please;)
Thanks in advance!