2000 Renault Scenic Gear Light and Engine Noise!

Engine Performance problem
2000 Renault Scenic Two Wheel Drive Automatic 73,000 miles

Hello
After starting the engine and driving for 4-5 minutes the Gear Light comes on at the same time as engine lurches and there is a louder engine noise. The Filter has been changed which reduced the occurrence of this fault but it still occurs half the time! I have to stop and switch off the car to get rid of the gear sign, but once running for a while, the fault does not recur. It does not seem to be speed related as it occurs at initial low speed or initial faster speed (on nearby motorway driving). Garage investigation has not identified a fault - so changed filter!
Gear Light Fault continues. Help!
In last 10 weeks, I have changed the radiator (two small leaks), the fan belt and the timing belt (preventive measure!).
Many thanks!