xine/xfmedia unable to play dvds

[Adam Hardy <adam.ant@cyberspaceroad.com>]

I don't know when it happened but I have done something to my system that stops 
it playing DVDs.

xine pops up a message saying that "source seems encrypted and can't be read"

I haven't done anything to the PC config recently except install updates for lenny.

I de-installed and purged the config for xine-ui and for libdvdcss2 and 
re-installed them to no avail.

Has anybody got any advice?

Thanks
Adam