Problems with session_unregister and / or unset()

Hey all! Sorry I haven't been around much lately. Hope things are well cscgal! :cheesy:

I'm working on a new function for the admin control panel of my site.

When a user logs in, it checks to see if it's a normal user, and then if not, checks to see if it is the administrator (me).

I've set up a select menu that allows me to log in as the "normal user" after I've logged in as admin. That part works fine, and I am logged in with admin permissions, yet, am viewing the control panel as the normal user would.

I have created a "switch" script that should unset the session vars that are registered for the normal user, which are company_id and cname, which hold obvious values.

However, when I use the script to unset the variables to either return to admin only, or switch to a new company, for some reason the session vars aren't being cleared, but it only happens on the page in which I registered the variables to begin with. The variables are registered in the header include, so this can occur on almost any page of the admin section...

Here is the contents of my "switch" script, which should unset the variables, and return me to the main page of the control panel...

Most of my session functions are fairly simple, so I'm totally confused on what may be wrong...

<?
session_start();
global $valid_user;	// username
global $company_id, $cname;

// I added this section to make sure it wasn't caching the page
header("Cache-Control: no-cache");
header("Cache-Control: post-check=0,pre-check=0");
header("Cache-Control: max-age=0");
header("Pragma: no-cache");
// End

session_unregister("company_id");
session_unregister("cname");
unset($cname, $company_id, $_SESSION['company_id'], $_SESSION['cname']);
header ("Location: $acp_location");
?>

Any Ideas???

Thanks in Advance!!!