I read all the thread on a similar post from 2006 but did not find an answer there.
I can not redirect on my localhost (Apache) or on my hosted site (Apache).

I was using a function created in a php course I took then switched to a basic piece of code with no other code.
This is a relative path but I also tired it with the full url. The reason I am working on this is it used to work but not all the time and I thought it had to do with my session cookie so I started eliminating variables. Te problem seems to be it simply won't redirect.

<?php
header("Location: {'td_index.php'}");
    exit;
?>

How about this:

header('Location: td_index.php');

Update: It isn't the php code. It is the browser. I am using FireFox and it fails with all code. IE 7 works will all the same code.
Any ideas?? Could it be a setting??

Sorry, really don't know then. Never had any issues with this.

Your code is good. The code I was using is from a php course I took and the instructor overkills everything. Yours is better for the test but now they all work, in IE 7. And none work in Foxfire.
IE 7 gives me a message that intranet settings are turned off. I think that is because I am using localhost.
I thought it might be Foxfire trying to ask me if I wanted it to remember my password but even simple redirects don't work.