Just wild guesses on my part:
(1) a buffer somewhere is too small; you might want to increase buffer sizes in k3b configuration.
(2) the packages that you have installed that k3b uses are incompatible with each other.
(3) the cables going to your DVD drive might not be good or not connecting properly.
(4) your computer's hardware might be just a little iffy.
(5) SuSE might simply not be fully compatible with your drive.
Your options are:
(1) try beefing up k3b's configuration and see if that works.
(2) see what packages are installed that k3b needs and if they appear to be the correct ones.
(3) check the DVD drive's cable. You might want to unplug and plug it in a couple of times to wipe away any dust that might be causing a bad connection. While doing that, be sure to ground yourself to the computer's case and keep yourself grounded so that you don't cause any static electricity damage.
(4) Run mprime's torture test for 24 hours and see if it causes any problems to show themselves. mprime is available at http://www.mersenne.org
(5) switch to a different linux distribution. I have found Fedora Core 4 to be rock solid so far and I have no trouble burning my DVDs in k3b.
...now, I can fairly say that if this was a windows problem I would have had it licked in 10 minutes. but I only have so much hair in my head to pull from all the swearing i've done to my computer in the past days...
Eek, windows is famous for these kinds of problems, including all of their ugly intractability that you are currently experiencing. Further, with windows your system might be working fine at first and then, suddenly, a problem like this just appears and won't go away, whereas linux tends to be much more stable regarding this (i.e. once you get linux to work it continues to work). I should know since I have experienced this kind of problem many a time on windows systems. Further, with windows, you don't have option #5 above (switch to a different linux distribution) since there is only one windows distribution (i.e. windows xp).