[dvd::rip] Some DVD-RW's don't work

I've got a slightly unusual problem with some video DVD's that I've recorded 
myself. When I try to read video from a TDK 2X  DVD-RW, I get the following 
message from DVD::RIP :

Job 'Determine number of titles' failed.

Executed command: dr_exec tcprobe -H 10 -i /dev/dvd && echo DVDRIP_SUCCESS

Last output was:


libdvdread: Using libdvdcss version 1.2.8 for DVD access
libdvdread: Could not open /dev/dvd with libdvdcss.
libdvdread: Can't open /dev/dvd for reading
(iodump.c) unable to open directory "/dev/dvd"


Exactly the same content recorded on a cheap DVD, such as DataSafe, reads 
fine, as does the same content from a TDK 4x DVD-RW. It makes no difference 
whether the disc was mastered on my DVD Video Recorder, or my computer; it is 
the disc itself that is the problem.

This isn't, in fairness, actually a DVD::RIP problem, because Xine is also 
unable to play the very same make of DVD (I've tried this with a number of 
identical TDK 2x discs, always with the same results). Xine on another 
computer, which is also using SuSE 9.2 but a different model of DVD drive, 
fails too. Interestingly, the disc can be mounted and the Vob files dragged 
onto Kaffine, yet anything that uses the disc device directly will fail with 
this particular type of disc.

So, can anybody shed any light on this? I would have thought it was a 
libdvdread problem, except I only updated it recently and I didn't think Xine 
used it.