Headers sent error msg on one server but not the other...

Hey Folks,
I have a script that times out the session if there is no activity in a
certain amount of time.  If there is no activity the HEADER()
redirects to the logout page and kills the session.  Everything works
fine on our test server, but when I test the script on the production
server, I get  an error "HEADERS ALREADY SENT..." after no activity.  I
know all this stuff needs to be on top, before any  XHTML.

The test server has reg globals = OFF and the production server has
them set to ON.  I can't change the any PHP.INI settings on the
production server. Both servers are running PHP 4.3.10.  Other than
that PHP installation is close to identical.   Any ideas / thoughts on
what's causing the production server to send this error out?  Something
to steer me in the right direction... I'm attaching a code snippet to
look at:

if (mysql_num_rows($result) > 0) {
$_SESSION["valid_user"] = $email;
}
elseif ($t_timestamp < $c_timestamp) {
HEADER("Location: logout.php");
exit;
}
Best,
CH
______________________________________
Craig Hoffman
ICQ / iChat: m0untaind0g
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