Hmm... I checked all the keys offline by running SHA(key+"?") starts with "00" as specified on https://en.bitcoin.it/wiki/Mini_private_key_format

On the website, if you plug your key in and run CheckClick(), does it show it is an acceptable answer?

Update:
Here's a quick port of the Java brute force into a Javascript website. If you want to take a look, it will lag your browser but gives the same output.
*removed*

Final Update:
The hashes within the page turned out not to be the right ones to check the puzzle, resulting in the output to be incorrect. The answer should be found via trying each possibility instead of calling the CheckClick() method.