CSRF Problem

[eluser]benjamin[/eluser]
Hi all,

Upon submitting forms, a client (Windows XP - tried on IE, Firefox and Chrome) of ours keeps getting:

Code:

An Error Was Encountered
The action you have requested is not allowed.

...indicating a CSRF problem. I have not been able to reproduce this error myself. The client's browser is configured to accept cookies ('accept all') and the system clock is set correctly. We are not relying on Ajax (just performing a plain old form submit).

config.php:

Code:

$config['csrf_token_name'] = 'csrf_pp';
$config['csrf_cookie_name'] = 'csrf_pp';
$config['csrf_expire'] = 220000;

Like I said, I haven't been able to reproduce this error - no matter how hard I try (switching browsers etc). Using CI 2.1.0
Any thoughts?