"Disallowed Key Characters" error from bad cookies

[eluser]Derek Jones[/eluser]
I think you might be the same user, but in case you just happen to be behind the same proxy, here's a link to my response to a similar issue an EE user experienced.

In CI, though, there are hooks available prior to the instantiation of the Input class to run through the cookies for you and either alter their keys or unset them.