My server admin recently upgraded to PHP 5.3 and I\'m getting a weird \"bug\" (or feature, as the PHP folks have it). I had mysql_real_escape_string around most
This is due to magic quotes, you should turn it off.
And here is how you turn it off: http://www.php.net/manual/en/security.magicquotes.disabling.php
You do it either via php.ini or by removing slashes from all variables in $_GET and $_POST, obviously the former is the recommended way to go.
As Will Martin suggests you can also change it via a .htaccess like this:
php_flag magic_quotes_gpc off
More info here: http://php.net/manual/en/configuration.changes.php