Thats quite interesting as the admin area does not load the vb2 or vb3 headers.
There is no call whatsoever in any of the admin files to printheader function. adm-index.php loads the page
Code:
Content visible to verified customers only.
You can try this test. First make sure all your uploaded files are NEW and try again.
Then if still persists try in adm-inc.php right before this
require "pp-inc.php";
add this
$skip_header="yes";