The errors could be a result of a change your host made to php.ini.
Tell your host to turn off PHP notices in your site's PHP.INI file. The correct setting for your account should be:
Code:
// Report all errors except E_NOTICE
// This is the default value set in php.ini
error_reporting(E_ALL ^ E_NOTICE);
I bet your host is using:
Code:
// Report all PHP errors
error_reporting(E_ALL);
http://us.php.net/error_reporting