Hi all,
I've just encountered the same problem with vCenter 5.5 U1 on a newly built W2K8-R2-SP1 server. I installed each component individually and hit the same issue at the end of the vCenter install. I was about to try CollinCo's solution of removing the server from the Domain etc, but I went to services.msc and noticed both the vCenter Server and VC Management webservices services had not started. Both of these servers had a "log on as" ".\Administrator". I changed them to log on as "Local System" and they both started fine.
George.