It's because of the translations in the strings:
<string name="date_format">yyyy MM dd HH:mm:ss</string>
<string name="dir_date_format">yyyy MM dd HH:mm:ss</string>
The filename must not contain spaces, "/" and ":", then it screws up.
Correct (or at least working) format could be: yyyy-MM-dd-HH-mm-ss
Would be a good idea to include this in an lang-pack update

Credits to XJ from xda, i'm just a messenger...