Just downloaded poEdit onto the computer of someone who is going to help me with some translations. However, when I tried to export a .po language file from Drupal (5.1) and open it in poEdit, I got an error message that said:
Couldn't load file xxx.po, it is probably corrupted.
The details added:
Broken catalog file: singular form msgstr used together with msgid_plural
Looking through the file, I found that it contained blocks of lines like:

