vCenter “Hardware monitoring service on this host is not responding or not available” in Hardware Status tab

 

Fix: In vCenter, select the VM host, Configuration, Security Profile (under Software), Firewall Properties, CIM Server, Options, Restart.

After restarting the CIM Server service, it can take a few minutes before the hardware status is updated.

Tested in ESXi 5.0

Reference: http://communities.vmware.com/thread/219556?start=15&tstart=0