Throwing my hat into the CRON ERROR ring as well. Site seems to work, just every periodic cron (15min delay) is tossing me this email now. Considering there is little ot no real traffice could it be due something caused by a NON-Event when processing CRON? Just guessing because the error message doesn't point to anything specific enough to track down and I delete the 10+ MB Debug Emails is sends occasionally :)
Database connect failed
Warning: mysql_error(): supplied argument is not a valid MySQL-Link resource in /home/cityofme/public_html/inc/classes/BxDolDb.php on line 444
Fatal error: Call to a member function getParam() on a non-object in /home/cityofme/public_html/inc/db.inc.php on line 83