Comment 2 for bug 722084

Same here on Ubuntu Natty
These are the versions used:

$ dpkg -l|awk '$2 ~ /^python[[:digit:]]|subdownloader/{print $2,$3}'
python2.7 2.7.1-5ubuntu1
python2.7-dev 2.7.1-5ubuntu1
python2.7-minimal 2.7.1-5ubuntu1
subdownloader 2.0.14-1

In the GUI everything works as expected and in my case also removing all existing subtitle files before running with cli interface.
But as long as there is an existing sub, the above happens.