After cleaning up your Virtual Center Database to get us back and running I came across the following

vCenter Server 4.x has a Database Retention Policy setting that allows you to specify when vCenter Server tasks and events should be deleted. Since this setting does not affect performance data records it is still possible to purge or shrink old records from the database using the scripts attached to this article. To access the Database Retention Policy setting in the vSphere Client, click Administration > vCenter Server Settings > Database Retention Policy.