dynamic php pages not refreshing, WTF??



ive got a sit where stuff on pages change when you update it from another page on the site.
On my computer if i change the page from the admin panel and go back to the other page and hit refresh it will reflect the changes that i made form the admin page.
But on a mates computer if i do the same thing, he does not see the changes i made on the admin page, the old data is still displayed no matter how many times he presses refresh, i even checked in the database and the data has changed, ive closed browser and reopened and still the old data remains. I have the meta tag of no-cache in the head of the php script and if you view the html of the page it is still there saying do not cache this page.
WTF is going on here?? why doesnt the data change on his computer but does on mine?
Try using this:
header("Expires: ".gmdate("D, d M Y H:i:s")."GMT"); 
header("Cache-Control: no-cache, must-revalidate"); 
header("Pragma: no-cache");
Put it on the very top of the page.