http://wordpress.org/extend/plugins/better-wp-security/
When this plugin is active it alters the query strings that WordPress attaches to the JavaScript and CSS files. This will break the loading of the Google Maps API by removing the “sensor” parameter. When this is removed, the Google Maps will not work. How can you check for this error? You can check the browser’s developer tools console log. Each browser is different on where the console log can be found but in most cases it can be brought up by hitting the F12 key and switch to the console log section. The error you’re looking for is:
The Google Maps API server rejected your request. The “sensor” parameter specified in the request must be set to either “true” or “false”.
UPDATE: This issue can be resolved by un-checking the option Generate Random Version Number in Better Security Tweaks
UPDATE 2: When performing a search in IE or Chrome, Firefox seems to be unaffected, the results will be shown. However, if you perform a second search from within the previous search results, you will receive a 404 error. At this time there is no solution other than to deactivate Better WP Security.
NOTE: This FAQ was written based on Better WP Security 2.18