Reverted recent commit, cookie_prefix was breaking things.
diff --git a/system/core/Input.php b/system/core/Input.php
index 7594a2e..fc2a550 100755
--- a/system/core/Input.php
+++ b/system/core/Input.php
@@ -226,7 +226,6 @@
 	 */
 	public function cookie($index = '', $xss_clean = FALSE)
 	{
-		$index = config_item('cookie_prefix').$index;
 		return $this->_fetch_from_array($_COOKIE, $index, $xss_clean);
 	}