I loaded the sample file on the ftp server as requested. It is called "BBC HD Crash.rar".
While investigating this problem some more, I have become even more confused as now I had it momentarily working
Enabled DVB subtitles in MP Config had not been crashing on BBC HD, for me, until around 2/3 days ago. Now BBC HD crashes for me every time, all whilst using svn from 23rd January (2nd most recent release).
This brings me to another issue... how can enable/disable subtitles within MP? I don't want to have to go to the configurator every time .
You can map a button to 'Next Subtitle', which is a much quicker way of turning on subtitles.