Whenever you insert Disc 1 of Adobe CS4 and run the setup, you will see a gray screen pop up "preparing for setup". Typically after this screen, you will get to the usual selection screen of what components to be installed as well as prompt for serial number. However, in Mountain Lion and some Lion machines, CS4 will be stuck at the gray screen "preparing for setup" and be frozen at the last 7/8 of the bar. I do notice a disk partition being mounted and disappear, but then again, that was in Lion. Mountain Lion just refuse to load the selection screen for installation.
