Yes, I have heard of this. The ORA-01555 isn't a VMware error state ... if you already applied the one fix by inserting/updating tables to reduce the amount of simultaneous queries done by vCloud ... there isn't much else that I am aware of to configure in vCloud Director itself.
I would highly recommend engaging Oracle for confirmation of next steps. Once this issue is addressed, it's entirely possible that you may have to restore a good instance of the DB where we didn't hit error states.