This looks to me likely to be a maintenance change has gone bad, The UK NATs system was originated by IBM before they abandoned it, IBM have a standard Sunday@midnight change control/maint slot as the only time that changes can be made so Monday mornings are the expected time for the SHTF if the changes failed, I suspect that poor quality Change Management was to blame.
This looks to me likely to be a maintenance change has gone bad, The UK NATs system was originated by IBM before they abandoned it, IBM have a standard Sunday@midnight change control/maint slot as the only time that changes can be made so Monday mornings are the expected time for the SHTF if the changes failed, I suspect that poor quality Change Management was to blame.