Users are not able to select the "Allow server to automatically load file" in the External Data wizard

Diagnosing The Problem

IE8 & IE9:
For IE you first need to know in what 'security zone' the Cognos portal
falls into. The easiest way to do that is to navigate to the portal
before doing the following:
(1) Go to 'Tools->Internet Options->Security'.
(2) Notice which 'security zone' is preselected, this should be the
zone the Cognos portal falls into.
(3) Optionally you can change the portal's 'security zone' by adding it
to the 'Trusted sites' zone.
(4) Once you know which 'security zone' the Cognos portal falls into,
select that zone and click on 'Custom Level...'.
(5) Find the setting called 'Include local directory path when
uploading files to a server' and enable it.
(6) Close all IE windows and load Report Studio again, you should now
be able to select the load file automatically checkbox.
.
Firefox 3.6+:
Follow these steps:
(1) Enter "about:config" in the URL field.
(2) Filter on following value:
"signed.applets.codebase_principal_support" (without the quotes)
(3) If not found, right click and select New->Boolean and name it:
"signed.applets.codebase_principal_support" (without the quotes)
(4) Set this setting's value to true.
(5) Click OK, close all FireFox windows, and load Report Studio again,
you should get prompted for a security promotion when selecting an
external data file, click Yes when prompted and you should be able to
select the load file automatically checkbox.