Your burner doesn't like the media you're using. Update your burner's firmware (remove any disc from the drive and close the tray then run the firmware updater) and try burning again. You could also try burning at 8x.
the second time in-a-row i burn it, it works 100%
I think it must be the burner. Recently it has not worked properly
Anyway, i'll try the firmware
This error happens unpredictably, not all the time.