After upgrading to the latest Limewire I too can't launch the file I've downloaded even afte r I've highlighted it. I never had this problem with eariler versions of Limewire. If I do a search for the file using Sherlock and open it that way it will start up itunes and play but if I just double click the file in Limewire or highlight the file and hit the launch button nothing happens other that what seems to be a click coming from the computer.