mp3 encode fails

[Kevin Lynch]

When I run get_iplayer --pvrrun it fails with this message

open3: exec of mplayer -nolirc -dumpaudio
/media/sf_iPlayer_Recordings/The_Blackhouse_-_Episode_1_b03bq7s5_default.partial.mp3.flv
-dumpfile /media/sf_iPlayer_Recordings/The_Blackhouse_-_Episode_1_b03bq7s5_default.partial.mp3
failed at /usr/bin/get_iplayer line 2791

The whole session can be seen here - http://pastebin.com/GB1ehRAj

I've been using this environment since april '13 ubuntu running in an
Oracle VM Virtualbox with shared folders saving the media in my
windows drive. I'm using Windows 7

Please can someone suggest a cause and remedy

thanks

Kevin