Hi!
Sorry about my broken English!
I have the same problem since few weeks!
Today I think i have found the solution!?
I am a slackwareuser - i have tried slackware 10.2 (kernel 2.4 and
2.6), ubuntu 5.10 and fedora core 4.....then i have tried dvdrecord
and nero for linux...i have tried 5 or 6 different medium...every time
the same error as you! (RW ok but R- and R+ nok)
But today i search for a new version of growisofs (dvd+rw-tools).
I don't found a new version but i found different versions for 486 and
686
(slackwarepackage: dvd+rw-tools-5.21.4.10.8.tgz and
dvd+rw-tools-5.21.4.10.8-i686-1jlp.tgz)
I deinstall the 486 version and install the 686 version and i was
really surprise: growisofs burn the medium (platinum 8x)
mabey important: i have upgrade my firmware to KS0B!
I have an Athlon XP 3000
Tomorrow i will trie to compile a source growisofs and i will borrow
from friends other mediums to test carefully.