Setting Form limit to -1 breaks forms and registration

Setting the "Maximum time to submit forms:" to -1 to disable it under security settings will produce the "invalid form" error and as far as I can tell completely breaks the registration page.

This is on fresh install of RC8 I'm using for testing purposes. I'm assuming this may be caused by my server setting but I really don't know.

If you need further server details or example forum PM me.