How to watch a DVD in Ubuntu?

I'm trying to play a DVD on Ubuntu 9.04. I've played DVDs on this machine before, but not with this OS. I've read this page, and libdvdread4 and libdvdcss2 are both installed:

$ dpkg -l libdvdread4 libdvdcss2
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Cfg-files/Unpacked/Failed-cfg/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Hold/Reinst-required/X=both-problems (Status,Err: uppercase=bad)
||/ Name           Version        Description
+++-==============-==============-============================================
ii  libdvdcss2     1.2.10-0.2medi Simple foundation for reading DVDs - runtime
ii  libdvdread4    4.1.3-4ubuntu2 library for reading DVDs

I've tried both totem-xine and vlc. Totem shows the name of the disc in the menu (progress!), but trying to play it shows a dialog box "An error occurred: The source seems encrypted and can't be read. Are you trying to play an encrypted DVD without libdvdcss?". VLC simply does nothing at all in the UI.

Both log some info to stdout/stderr. They have slightly different libdvdnav versions, but both display exactly the same CSS info:

libdvdread: Using libdvdcss version 1.2.10 for DVD access
libdvdnav: DVD Title: SHINOBI
libdvdnav: DVD Serial Number: 359632fa
libdvdnav: DVD Title (Alternative): 
libdvdnav: Unable to find map file '/home/ken/.dvdnav/SHINOBI.map'
libdvdnav: DVD disk reports itself with Region mask 0x00fe0000. Regions: 1

libdvdread: Attempting to retrieve all CSS keys
libdvdread: This can take a _long_ time, please be patient

libdvdread: Get key for /VIDEO_TS/VIDEO_TS.VOB at 0x00000137
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_01_0.VOB at 0x00000817
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_01_1.VOB at 0x00000c41
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_02_0.VOB at 0x0002cfca
libdvdread: Elapsed time 0
libdvdread: Get key for /VIDEO_TS/VTS_02_1.VOB at 0x0002e419
libdvdread: Elapsed time 0
libdvdread: Found 2 VTS's
libdvdread: Elapsed time 0

to which Totem also adds:

demux_wavpack: (open_wv_file:127) open_wv_file: non-seekable inputs aren't supported yet.

though it doesn't seem related.

I tried another DVD, and it worked fine (in Totem, anyway). It's a homemade DVD from camcorder footage, with no menus or chapters. Update: another commercial DVD works fine here -- the second DVD from this 2-DVD set, in fact, so same region, same studio, etc. I also tried my first DVD on a different machine (with a different OS), and it plays fine there, so it's not simply a bad DVD.

Is it possible there are DVDs which libdvdcss2 simply can't crack?

I tried a newer version of VLC on a different computer/OS, and it worked there. So I eventually upgraded to Ubuntu 9.10, and even though it has the same version of libdvdcss, it works fine now.

So I have no idea what was going on, but it's gone now. As computer problems come, computer problems go.