Hyundai Repair: black smoke, mile intervals, scan tool

Question
I have an 03 Accent 1.5 CRTD aprox 40,000 miles and serviced at 10,000 mile intervals. The last  39,000 have been trouble free. In the last week this has occured twice. Started the car --no problem drove 50yrds and turned off engine.  When I went back to the car it turned over ok but I had no responce when I depressed the accelerator and clouds of black sooty smoke were blasting from the exhaust leaving a thick sooty deposit on the ground. When I switched the car off and on again it seemed to be ok. both times this has happened I have only moved the car a few feet and then switched off.  is this a real problem or just an aberation

Answer
only thing i can come up with .an this is with out running the scan tool for the right answers,i would have to say it is to do with the injectors dymping fuel so maybe a good cleaning an see what happens, this si all i can say with seeing scan tool readings