Writing on DVDs
Is there a type of pen or marker I can use to safely write on DVD-R/+R? I have noticed lately that if I burn a video file to a DVD, and then write on the DVD with a marker-type pen (usually a Sharpie brand fine-point marker) it damages the DVD somehow. When I'm watching the DVD, the video freezes and then either jumps ahead or just stops playing entirely and goes back to the menu. But if I don't write on the DVD, there is no problem watching it.
I can't just stop labelling my DVDs, because then I will not know what is on them. But I don't want to damage them, either. What can I do so that I can label the DVD without damaging it? Preferably without buying a DVD stamper/stomper or whatever those things are called.