SUMMARY
Information about using domain login to correct vCenter connection issues
ISSUE
After upgrading to vSphere 5.5, some users have reported issues connecting to vCenter with their VBAs.
In some cases, a domain login may be required to resolve this issue. Update your VBAs configuration to use a domain account to connect to the vCenter server. Additional details are available in VMware's knowledge base.
How vCenter Single Sign-On Affects vCenter Server Upgrades
How vCenter Single Sign-On Affects Log In Behavior