Have a look at your themes search.php file, if everything looks okay there try disabling any search related plugins you have as they might be interfering with mystique.

If that's still an issue turn on wp_debug

I don't have any search related plugin activated at the moment.

I inserted the
define('WP_DEBUG', true);

code in the wpconfig.php file but the theme got corrupted and said there is a missing string in the function.php file

Any clue?

Still looking for a solution

Hi, i know a new website (PCWatch.com) which met this problem as well, you can contact the webmaster

Why don't you just answer me over here?