Encrypted DVD runs in the internal but not in external USB Drive

Hi

Im trying to play an original encrypted DVD with my NEC 1300 A housing 
in an external USB 2.0 IDE enclosure, but it doesn't work.
I get messages like:
------------
libdvdread: CHECK_VALUE failed in ifo_read.c:1862
for vts_attributes->lastbyte + 1 >= VTS_ATTRIBUTES_MIN_SIZE
...
libdvdcss error: css error: ioctl_ReadCopyright failed, make sure .....
...
libdvdcss debug: could not check whether the disc was scramled
...
libdvdcss debug: cracking title key
libdvdcss debug: read error
libdvdcss debug: read error, resorting to secret arcanes to recover
...
libdvdcss error: fatal error in vts css key
libdvdread: Error cracking CSS key for ...
------------
Versions:
libdvdcss: 1.2.8
libdvdread: 0.9.4

DVD without any encryption running well in this drive!
The encrypted DVD runs well in my internal drive.

Then I'm using Windows the encrypted DVD runs with in the internal as 
well as with in external drive.

I dont think it's a problem with libdvdread but I hope someone can give 
  me a hint !

atsch