Host sensor data is not updated. The Query Service is not available or was restarted, please retry.
I have run across this issue a couple of times now when shutting down a few of our hosts (including vCenter) and them booting them all back up at the same time in the lab. Due to the way that the VMs were booting back up, some of the VMware services were not starting properly and would result with the inability to view the Hardware status tab in vSphere.
To resolve this issue, simply go through and restart the services on your vcenter box and you should be back in business. Restarting the VMware VirtualCenter service specifically should take care of things (it might ask to restart VMware VirtualCenter Management Webservices as well... that's fine).
As a side note, I did try going through ADSI and changing some values, however I feel this is more of an issue due to the way your VMs come alive and associated dependencies (SQL backend, DCs, etc.)
Hope this helps!