Wow,... About the thing with your RW.
I have to agree with ffg.
I think the same.
The only explanation I have for this is, that the cert.-speed of your re-writeable disc is much lower.
You may should update the fw of your DVD-Burner, if you can.
It might not calibrate it right, for those DVD-Medias (maybe not in fw-db).
Else I couldn't understand, how it can give you such a problem.
You also may try other DVD-Rs.
Ah,... I don't use K3B usually, because I simply don't like it.
This may also the case.
Do you have a Win-PC and can do it there with some good apps (CCD, Alc120%, DVD-Dec.)
What is your DVD-Burner-Model?
PS2 V7/DMS3 V2 (FW:2.4b7); Seagate Baracuda 200GB
PS2 V7/CC1.0 (FW:34 hacked v2 BM:2.1.6); Maxtor DiamondMAX9 PLUS 160GB
PS2 SCPH-30004R; NoMod+NoLaser
3xSony MC 8MB
MAX/Datel 16MB with Boot-CD
Custom FMCB 1.8b+ Beta-Build, my AIO 0.5, Sony&xRhino-Linux