This issue occurs when users overcommit the resources for a Provider vDC which contains PAYG Org vDCs.
The values for 'Total Reservation Sold' (for all vDCs in a given PvDC) should be less than Available Reservation in the PvDC Resource Pool.
As PAYG use Resources from the Provider VDC, it is possible for them to cause contention with the other Organization VDCs and as such are disabled when the PvDC Resources are not managed correctly.