I might be a little late with this but maybe you should have gotten a Lowrance? My LCX 25C works well and my old X-85, after all these years works flawlessly.
ps. Oh, disregard the above. Perhaps you should give Humminbird another crack at it. Hey, all the really good fishing dudes with those coloured shirts and sexy Humminbird logos all say they're the best they've ever used! C'mon Paul...buy another Humminbird. They already told you that they're aware of their limitations so it's only a matter of time before you're really somewhat happy with one.