Refresh PHP

Hi people! Did anyone get this situation? I'm creating a Site that uses 3 session variables. One of them I always print at the top of the page, it's the name of the user. There is a link that calls the function session_destroy(). Everytime that I follow this link and log in with another user, that session variable printed doesn't change, but if I press F5 in IE or Netscape them it brings the right user. I can't make the page return the current user login, it always came with the last user logged. I tried to add some headers to set no cache in all php pages, but it doesn't work. Anyone can help me??? Thanks PS: Sorry about my poor english... Maurício Valente