2006, 1.6 VW Polo - EPC and Handbrake warning lights Flashing - Thapza

I'm driving a VW Polo 1.6 and in South Africa. when driving above 110 Km/h (75miles/hour)the car showes an EPC warning light together with the Handbrake warning light and when this happens the speedometer needle falls back to zero with no adverse effect on the performance. but when driving in less than 75miles /hour this does not happen....what can be the cause of this?