Keep getting mails about xdebug
Check your php.ini settings; if you have a separate xdebug.ini file under /etc/php5/conf.d containing a zend_extension=*.xdebug.so line, it's possible that it already exists in the main cli/php.ini file too, so when it tries to load the second config file it'll produe the already loaded error message.
Looks like you have more then just a job loading xdebug.
Look for more lines inside your /etc/cron.d/ folder files and inside /etc/php5/conf.d trying to load xdebug.so.