Cannot access retail DVDs with external drive

Hi all,

the following drive, when attached via USB (or Firewire) fails to do
_anything_ with retail DVDs. I can read burned CDs just fine, however.

cd0 at umass-sim0 bus 0 target 0 lun 0
cd0: <PLEXTOR DVDR   PX-755A 1.06> Removable CD-ROM SCSI-0 device 
cd0: 40.000MB/s transfers
cd0: cd present [2042992 x 2048 byte records]

(cd0:umass-sim0:0:0:0): READ TOC/PMA/ATIP {MMC Proposed}. CDB: 43 0 0 0 0 0 1 0 c 0 
(cd0:umass-sim0:0:0:0): CAM Status: SCSI Status Error
(cd0:umass-sim0:0:0:0): SCSI Status: Check Condition
(cd0:umass-sim0:0:0:0): ILLEGAL REQUEST asc:24,0
(cd0:umass-sim0:0:0:0): Invalid field in CDB
(cd0:umass-sim0:0:0:0): Unretryable error

This is with a recent kernel, and I'd like to know, if there are any
knobs I could/should try to debug this further.

Thanks,
Ulrich Spoerlein
-- 
"The trouble with the dictionary is you have to know how the word is
spelled before you can look it up to see how it is spelled."
-- Will Cuppy