Hi folks, Someone I know on Twitter posted this link: http://arstechnica.com/apple/2012/07/confirmed-mountain-lion-sends-some-64-b... # Information included with the first Mountain Lion GM now # corroborates the connection to 32-bit graphics drivers as # the culprit. While Mountain Lion is compatible with any Mac # capable of running a 64-bit kernel, the kernel does not # support loading 32-bit kernel extensions (KEXTs). Furthermore, # Macs with older EFI versions that are not 64-bit clean won't # load Mountain Lion's 64-bit only kernel. # # As you might have already guessed, graphics drivers are KEXTs # under OS X. And the GPUs in some of those early 64-bit Macs were # deprecated before 64-bit KEXTs became common. Since those older # drivers are 32-bit, Mountain Lion won't load them. We believe # Apple decided it was better to draw the line in the sand for some # older machines rather than invest the resources into updating the # drivers for these older GPUs. So some people will find that they won't be able to upgrade their Mac's to the new MacOSX and so may wish to experiment with alternatives rather than stick to the older OS. -- Chris Samuel : http://www.csamuel.org/ : Melbourne, VIC