Sessions Variables and refresh pages

Hello, this is the fourth time i wrote expecting some answer from somebody with more experience than me. I have a protected page , i ask for user and pass and save these variables as session variables, with session_register. When the user submit this page.. this variables are registered, in the next page, i do some queries using a substr of REQUEST_URI and displaying 2 selects results and 1 update. When i remove the access-control page all works fine, but when i set the session vars, the first time i see the results, i need to refresh/reload the web page to show the correct results of the queries, otherwise the page source shows "data missing... post operation... refresh..." Please, how can i avoid the manual refresh ? Karina Gomez