More fiddling around... KDC Service requires port 88 to start.
Netstat -abn shows that vpxd.exe is using port 88. When I installed vCenter, I had chosen port 88 as port 80 was already in use by IIS... I have now disabled IIS and want to move vCenter back to port 80.
Now, anyone has a clue how I can change vCenter back to port 80?