Hope I'm posting to the right place. Why is it that certain video types (avi mpeg, mpg, etc) sometimes play on my imac and sometimes don't? Doesn't seem to be any rhyme or reason. For example, a file with the extension .avi will play, but a file with the extension .AVI, won't. Also, I have downloaded the latest version of the windows media player, but when I try to open it, the icon in the dock just bounces and the player will not open. I have downloaded flip4mac and that works, but why won't the windows media player work? Very confusing. Thanks for any help.