Header() redirect

Is there another function that does the same job as Header() I'm creating a forum, and when a user sends a message I call a function that checks name, password etc, then updates the DB and then calls the Header function to redirect the page. This would be fine except I am also using session library files that have the html headers already created, thus, while the redirects (it still redirects) I get the standard Warning: Cannot add header information - headers already sent by .... message, I know where the problem is but can't solve it without changing many function of the forum functionality. I have tried using plain javascript and this does work but there is again a split second delay that is very annoying. Thanks.