Had the same error today on an ESX 3.5.0 build 82663 server, it disconnected from the Cluster it was in and wouldn't connect in VCentre
An internal error vmodl.fault.HostConnection. It then went through the wizard of adding a host but failed at 9%
Rebooted ESX host and same fault when trying to connect in VCentre. I could connect directly to the ESX host itself and see the hosts (all down)
I had to reboot our server hosting VCentre and then connect worked straight away on this ESX host
VCentre was the issue for my fault