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.
Bug tracker
Setting Form limit to -1 breaks forms and registration (fix completed in vcs)
Comments / History
Posted by thecoalman (Former Team Member) on Dec 10th 2007, 08:03
Leaving it at the default 7200 doesn't cause any problems. Setting it to 0 probably would because you're giving them 0 seconds to submit the form. 
Posted by thecoalman (Former Team Member) on Dec 10th 2007, 08:06
I should add the text says set it to -1 to disable, most of the other settings are 0 to disable but not this one.
Assigned ticket to user "Kellanved"
Action performed by Kellanved (Former Team Member) on Dec 10th 2007, 08:46
Changed ticket status from "New" to "Unreproducable"
Action performed by Kellanved (Former Team Member) on Dec 10th 2007, 08:51
Posted by Kellanved (Former Team Member) on Dec 10th 2007, 08:51
I can't reproduce that at all. Works fine for me.
Changed ticket status from "Unreproducable" to "Fix in progress"
Action performed by Kellanved (Former Team Member) on Dec 10th 2007, 18:19
Linked ticket with changeset: r8273
Action performed by Kellanved (Former Team Member) on Dec 10th 2007, 18:35
Changed ticket status from "Fix in progress" to "Fix completed in CVS"
Action performed by Kellanved (Former Team Member) on Dec 10th 2007, 18:35