I used to run Limewire/OS X with no problem. Then I tried to upgrade and got a anew icon on the dock. Then I tried to purchase LiimePro and it would not install. I put everything in t he trash and started over. Now, whether I try to download basic or Limepro, I get a screen before the dowonload is completed or after I try to open the .sit which says: Unknown zip header format encountered--this operation cannot continue."