The computer ComputerName is joined to a cluster.
This might affect other versions of failover clustering but this happened on windows 2008. The Add Node Wizard checks the server’s cluster service if its disabled or automatic. If for some reason its still set to startup type automatic that message will come up. To fix this issue all you have to do is set this to disabled again. That is assuming that is server has been correctly removed from any previous clusters.
Many thanks for this useful piece of advice. I was just about to rebuild my whole environment until I came across this simple fix.
I'm glad that tip could save you time.