Check whether your burner can handle the type of x8 media you used. I had almost the same problem some months ago. Actually it was worth than your experience. It turned out a media problem, though it was a good brand.
Second, I updated the firmware. It did not help much, but in your case it might be a solution.
I surpassed this problem changing media (using RICOHJPN02) and burning with CloneDVD2 speed set to x8, not "Maximum" speed.