Skype joins the list of applications that the Mac OS X Leopard operating system cripples or kills.

At this point, users are complaining that the VOIP (voice over IP) application Skype and the online game "World of Warcraft" are breaking after being activated from within the firewall. Some Adobe Creative Suite users on forums have also complained about performance under Leopard, with InDesign not launching, Photoshop running but occasionally crashing on launch and Illustrator running but crashing on quit.

At issue is a new firewall feature that was introduced in Leopard: the identification of applications via code signatures.