Why does unserialize in PHP keep returning false?

I've just written the easiest script in the world, but still I can't get it to work, and it's mighty strange. I want to use jQuery to catch some input field values and serialize them with jQuery's `serialize()`. I then send the serialized string to the server to unserialize it. Here's the output I get from the serializing in jQuery, this is what I send to the server. ``` field1=value1&field2=value2&field3=value3 ``` And here's the function, ``` public function unserialize_input() { $str = $this->input->post("user_values"); $unserialized = unserialize($str); var_dump($unserialized); } ``` As I said, if I go "echo $str;" I get "field1=value1&field2=value2&field3=value3", so the string should be unserializable. However, I always get the same error message and the `var_dump($unserialized);` always returns bool(false). Here's the error message I get from CodeIgniter, the framework I'm using for PHP. ``` Severity: Notice Message: unserialize() [<ahref='function.unserialize'>function.unserialize</a>]: Error at offset 0 of 41 bytes bool(false) ``` I'm using MAMP and run this locally at the moment. I read something about `magic_quotes_gpc` being OFF could cause this locally, but it's enabled. What might be wrong?