Yes, this could well be the DVD drive's region code not matching the region code on the disc.
BBC discs are probably Region 2 and your DVD drive may be set to Region 1.
Poor old WMP has to try to interpret the error code coming from your drive into something more meaningful but there probably isn't any standard way of reporting this problem so it just has to guess.
DVD drives often have their region code set in their driver properties and have special software to stop you changing the region code often. (You may only get a fixed number of changes before it stops you changing it again or you may only be allowed to change region once a month.)
Having region codes on DVD players and discs was at the insistence of the Hollywood studios as a (very poor) anti-piracy measure.
