Yesterday I migrated my four production hosts from Virtual Center 2.5 to vCenter 4.0. I have four vm's that are load balanced and were on different hosts prior to the migration that worked fine. But since the migration to the new vCenter they cannot ping each other unless they are on the same hosts. The odd thing is I can ping the load balanced servers from a different VM on a different host on the same IP segment. They just can't ping each other when on different hosts. Again this only happened after I migrated the hosts to vCenter 4.0. The hosts are 3.5 Update 4. Will be upgrading them to vSphere in the next couple of days. I am open to suggestions.