DVDs won't play on my computer; while I can mount the dvd fine, (HAL and DBUS take care of this) playing it always results in an error telling me that "/dev/hdc is busy." I get a similar error if I click the "eject" button in Nautilus, ("eject: unable to open `/dev/hdc'") despite the fact that the disc appears to unmount properly.
I *should* have the proper software installed for dvd playing, and I can play individual VOB files on the disc.
Usually the DVD must not be mounted to be played.
I've tried it with MPlayer and Totem-xine, and I get similar errors from both:
"Failed to open device /dev/hdc for reading: Permission denied"
"Couldn't open DVD device: /dev/hdc"
This same behavior seems to occur regradless of whether or not the disc is mounted.
have you got libdvdcss installed?
imagination is more important than knowledge!
Maybe a side thought, but just covering all bases: did you add your user to the 'optical' group?
gpasswd -a <user> optical
Also, as totzo mentioned, make sure libdvdcss is installed.
 Sorry about the typo..... appreciate the correction!
you have to type it the other way round:
# gpasswd -a USER GROUP
so in your case:
#gpasswd -a dan optical