Speculation, but could have been: Going into the corner too hot, coming out of the corner too hot (throttle induced oversteer), or just not knowing how to drive...

I was once at an "open track day", and this group of kids brought a Nissan GTR and a Skyline. They couldn't drive these cars, there was a Miata out there that they couldn't keep up with. I never actually saw them out on the track, so all I have is second hand reports via stories that were making the rounds of the pits, but I do know they didn't stay very long.