How can I fix my Stoves Double Oven Rotostar & Grill, Model Q 900 GRF DO?

Both ovens and the grill regularly fail to re-ignite and then go into soft lockout mode with the green light on the control knobs flashing. The oven (micro-computer)can be reset by turning the control knob to the off position and then turning the oven back on.
Does anyone know the reason for this to keep happening and is there an economic repair available?
The oven is 13 years old and otherwise clean and undamaged.