I have 2 ESXi 4.0.0 servers that have been running for a couple years. Saturday morning. I got a call from the help desk saying that several of the guests were down. I opened up my vsphere client and connected to my vcenter server. It told me that server 5 was disconnected and all of the guests on server 4 were not responding.
I tried shutting down the guests, but I was unable to do so. I was able to ssh into the servers and reboot them both from there. They both came back up and all the vm's came back up, but I am still unable to connect server 5 to the vcenter server. When I try, it tells me the ssl key has changed. It then startes trying to connect. It gets to 9%, then I get disconnected for about 3 - 5 minutes. In the event viewer, I get the message "The VMware VirtualCenter Server service terminated unexpectedly.". It is then automatically restarted.
I am able to connect to server 5 directly with the VSphere client and everything seems fine. The only thing I have noticed is that when I am looking at the client and it is connected directly to a host instead of to the VCenter server , all of the guests seem to randomly blink on the list on the left side of the window.