I've noticed something strange in my vista OS recently: the control panel button in my start menu wasn't working. It wouldn't respond when I clicked on it (although, when I edit the properties of the button and make it a list, I can still see all my control panel items), and not only that, it wouldn't show the icon (see the attachment for a better idea of the situation).
Another detail that might be useful is that when I switch to the classic menu, the control panel icon is there (System tools menu), BUT it seems to take me to the desktop for some odd reason. Stranger than all of that, the control panel is still where it normally is (i.e. I can still use it and all of it's features).