Exactly what Clinton said! I have had burns go awry with k3b (using Ubuntu, which is my choice for the main O/S these days) and simply forcing a slower burn speed fixed the problem. Also, it's always a good idea to let the cd or dvd burn without a bunch of other things going on in the background. When I used that "other" operating system, I used Nero and it was the same story... I only use k3b now. Find a time when you can let it do its thing without any word-processing, file processing, or internet browsing going on at the same time. Close all the other applications. Pick a burn speed that's slower than 1/3 to 1/2 of the default. That works well for me.