SCVMM 2012 : Adding ESX 4.1(i) hosts will fail when using root account
Maybe this is a very small blog post , but I think it could help some people out 
When you want to add your physical ESX 4.1 hosts with the root account and it does not succeed ( getting an access denied ) , it means that your hosts are in lockdown mode !
Switching off “Lockdown mode” gives you back the possibility to add your hosts with your root account.
Hope it Helps ,
Kenny Buntinx