Thanks heaps you're a legend! Ok I have been playing around from Google searches... I added the following at the end of insert.php, which I'm guessing I should now remove yes?
// Kill all session variables
Also on signup.php which is the sign up form I was reading would be good to add some META's should I keep them or is it pointless?
<meta http-equiv="expires" content="Sun, Dec 31 1970 12:00:00 GMT" />
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="pragma" content="no-cache" />