I got a iMac with Leopard and I would like to upgrade to Lion. I have a retail copy of Snow Leopard so as to install them first. When I open the DVD it shows the Installer and some other folders. I open the Installer and then it shows an error: "Mac OS X Snow Leopard cannot be installed on this Computer" I open the folder with the instructions and I find the hardware requirements. I check the "About this Mac" and everything seems to be OK. 4gb Ram (Snow Leopard needs 1gb) 146gb Free Space Intel Processor etc... I tried to boot to the DVD by pressing the C button when starting and it shows the same message again. What should I do? Any help would be appreciated!