I'm running an intel iMac and tiger, and I'm trying to upgrade directly to snow leopard. But, when I put the installation disc into my cd drive, the icon doesn't show up on the desktop. My iMac just beeps every 5 or so seconds, then after a minute ejects the cd out. It can read all other cds, but the snow leopard install disk happens to be an exception. Any suggestions on how I can install snow leopard? EDIT: also, the snow leopard install disk doesn't seem to be damaged; it runs fine on my sisters leopard macbook.