[ubuntu] Why do I have PNJ and ID3 files associated to JPG and ZIP files?

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http://ubuntuforums.org – Hi I was backing up my home dir when I found many ".jpg.pnj" and ".zip.id3" files. The ".pnj" files seem to be thunbnails for the ".jpg" files I have. On the other hand, no clue about the ".id3" files, since the program file tells me they are audio files. I couldn't find any of these files not associated to a ".jpg" or a ".zip" which already existed. I tried googling, but all I've got was how to tag MP3 files or convert image formats. :( Can anyone tell me which program creates them? Is there a way to avoid suc (Hardware)