For some reason, Vmware has decided to disable the Web Access service in ESSX 4 by default. You will find this out if you attempt to click on "Log into Web Access" on your Vmware ESX 4 Welcome Page on a newly build ESX 4.0 server. You will get the following error "503 Service Unavaliable". Do not panic
To resolve this you should SSH into the ESX box and type the following
service vmware-webAccess start, to start the service
chkconfig –level 345 vmware-webAccess on, to set the service to start at boot.