Mmm, tried output buffering with no joy (forgot to mention that in my previous post - sorry).

I've checked the session variables, and it's nothing to do with them (they're all being created fine, and all destroyed when the user logs out). However, after logging out (which destroys the session variables) and going to .com/secure I get a blank page (or the error if error reporting is turned on) instead of being bounced to the ../index2.php page.