I have an issue with the gearbox. Drive gear some times slips as I am taking off from stand still. I will put into drive from parked position and will not go into gear. The light on the dash says it is in drive also the N light flashes as well and car does not move. I then turn the car off and then back on and I can drive off. NRMA said it maybe something like a computer problem. Has anyone come across this before? Is it a computer issue or does the gearbox need replacing?