Well .. actually this sounds like warez talk which we are not allowed to do. But it sounds like you need to enter a serial number for the game.

LW itself will not launch programs. You need to open it directly from the Library folder. ie: right-click the listing, choose Locate on Disk from the menu that appears. Then open it from there.

Did you scan the item with your anti-virus to check it's safe?
Did you download via torrents or via gnutella network?