Running Software Update

Hello -

I am trying to update some of our VMWare ESX 4.1 servers' 6/i controllers. I keep getting an error in ItAssistant (Version 8.9.0) that "The servers host key is not cached in the registry". These are not new servers, we've had them for quite some months now. I have removed them from the Ranges and re-discovered these servers but still getting this error. Has anyone see this and how did you fix it?

Thanks in advance,