For a few weeks now I’ve had both of the ESX hosts in my main cluster display not responding in VC. I’ve tried reconnecting them but this only solves the problem for a minute or two. Restarting the VC service will fix this for 10-15 minutes but it still falls back to “not responding”.

VMware has a checklist of stuff to check when an ESX host displays “not responding”

VMware Checklist

I made it down to number 8 before the problem seems to have finally been fixed. Time will tell as always.

VMware KB#1003490 “Restarting the Management agents on an ESX Server”