We had this errror too:
inherited from com.vmware.vim.binding.vim.fault.InvalidLogin: Cannot complete login due to an incorrect user name or password.
Our vcenter, has two dns names, due to legacy reasons. We had to put both of them in /etc/hosts.
vcenter:~ # cat /etc/hosts
127.0.0.1 vcenter.domain.com vcenter localhost
external-ip vspherecsl.domain.com vspherecsl
After this, we just followed http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2037952
and it worked.