What you are describing is the default position adopted by the eat (electronic automatic transmission) ecu when a fault is logged in the eat ecu.
In Rave, the land rover discovery workshop manual, there is a list of about 19 faults which will trigger this default position.
So you need to have your fault codes read by a, test book, nanocom or hawkeye diagnostic tool, other fault code readers may not give a true reading as discovery td5 is not obd2 compliant, using landowners own code system.