Okay, I have an ibook g4, Os X 10.4 and for some reason, when I try to download certain applications, it just doesnt recognise them. The little icon beside the download is blank, and it says there is no default application to open it. This has happened when I have tried to download several audio files that my friends have sent me, and also when I tried to download windows media player for macs. What am I doing wrong? Please help!