Comment 3 for bug 397194

Had exactly the same problem. As far as I remember the permissions where as follows:
bill@mythtv:/var/lib/mythtv$ ls -l
total 8
lrwxrwxrwx 1 root root 15 2009-07-18 02:28 music -> /storage/music/
lrwxrwxrwx 1 root root 18 2009-07-18 02:28 pictures -> /storage/pictures/
drwxr-xr-x 2 mythtv mythtv 4096 2009-08-15 23:56 posters
drwxrwsr-x 2 mythtv mythtv 4096 2009-08-17 09:17 recordings
lrwxrwxrwx 1 root root 15 2009-07-18 02:28 videos -> /storage/videos

I did "sudo chmod g+w posters/" (checked in history), which changed posters to:
drwxrwxr-x 2 mythtv mythtv 4096 2009-08-15 23:56 posters

This fixed it.