The invention describes a method of shutting down a high pressure discharge lamp (1) in which a pair of electrodes (2) are disposed in an arc tube (3). This method comprises the steps of reducing the lamp power (PA) to a reduced operation level that enables the maintenance of an arc discharge between the electrodes (2) in a transition state from a lighting state to an extinguished state; driving the lamp (1) at the reduced operation level such that that the lamp (1) cools down; monitoring the lamp voltage (U) during this lamp power reduction process and during driving of the lamp (1) at the reduced operation level with regard to a defined discharge process stability criteria and increasing the lamp power (PA) if the discharge process stability criterion is not satisfied; completely shutting down the lamp power (PA) after sufficient duration to allow the lamp (1) to cool down to a state in which the gas pressure is such that the lamp (1) could be reignited shortly after being extinguished. Moreover the invention describes an appropriate driving unit (7) for driving a high pressure discharge lamp (1) and an image rendering system (40), particularly a projector system, comprising such a driving unit (4).