This is a known issue, having to do with Historical Data collection being enabled (non-zero) in the VMWare Agent Properties on the Agent Status screen.  Change to 0 and deactivate/reactivate the agent, and it should correct the issue.  Please open a level 1 ticket with support via phone if you need more assistance.
VMware vCenter Server service stops or restarts when Data collection starts I'm using vCenter Server 5.0 Every time I start collecting data, vcenter service stops or restarts, if I stop collecting data and disable the agent, the vcenter service starts again and works well. Please any help!  Thanks in advance
VMware vCenter Server service stops or restarts when Data collection starts