1999 Renault Clio • 85,000 miles

Car for the first few miles cannot be put under any pressure once in top? Gear otherwise gearbox wil bang sometimes violently into a lower gear andthe the gearbox warning light will cime on.
The engine then has to be stopped and restarted to clear the fault and for it to go up through the gears normally. Its very scary someone said check transmission fluid.
November 3, 2012.

It sounds like you need to take it to a transmission specialist as there is some mechanical issue in the transmission that is near catstrophic failure possibly and could pose a danger. Make sure you take it to a transmission repair shop and not a standard repair shop as trnsmission require special expertise and tools to repair and diagnsose them properly.