i've been happy with xine for other vid formats, so i thought i'd try to play a dvd - xine not happy

compiled xine from source with xine-ui (newest version)
i have all pluggins installed (i think)
i have symlink /dev/dvd => dev/hdc (dvd drive)
i have group "cdrom" which has rw permissions to /dev/hdc - i belong to this group
xine-check comes out all ok.
xine recognizes the dvd (shows title + region)
when i press play, i get error:

- The source can't be read -
- maybe you don't have enough rights for this, or source doesn't -
- contain data (eg. not disc in drive). (Error reading NAV packet) -

haven't found any other postings of this.
any ideas?

tried using a decent DVD player? http://mplayerhq.hu it will give you a lot more useful troubleshooting messages too, if it acutally is an issue with permissions.