Have you recently tried to upgrade the guest? If so you might want to roll back and to a controlled license re-activation on your hosts. Please mind that the reactivation process can be disruptive to your traffic flow.
yssp just following up - did either of the answers above help? If yes, please mark it as an Accepted Solution so other users with your same issue can quickly find resolution (and whoever gave you the answer which worked gets points). 🙂