Apple today released Airport Client Update 2009-002 which addresses minor issues in Snow Leopard’s wireless access software. It is recommended for all Macs running Mac OS 10.6 (Snow Leopard) and includes fixes for the following: • Inability to turn AirPort on or off in some cases after upgrading from Mac OS X Leopard • An occasional loss of network connection when using Wake on Demand • Inability to create a computer-to-computer network, or share the Internet connection on some MacBook, MacBook Pro, and Mac mini computers The update weighs in at 13MB and is available in Software Update and at Apple’s Support Web site.
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Apple releases patch for AirPort clients