MySQL errors appear only on Chrome [mysql_real_escape_string(), : mysql_error()]

Question

Unfortunately I'm getting MySQL Warning messages. For some reason, they only appear in Chrome.

Here are the errors;

Warning: mysql_real_escape_string(): 16 is not a valid MySQL-Link resource in /../wp-includes/wp-db.php on line791

Warning: mysql_error(): 16 is not a valid MySQL-Link resource in /../wp-includes/wp-db.php on line 1105

I have turned off WordPress getExternalUsers because of problems like above. However, I'm still getting those errros.

Please tell me how to fix the errors.

Thanks,
A.T.

BTW: I followed this tutorial to get where I am, then just set the qa-config get external users to false. I still need to get_header() from WordPress, which is why I still require the other features from the tutorial.

FYI: I've replaced my actual absolute directory path with /../ for security reasons.