I purchased the Snow Leopard Family Pack through Apple. Installed for the first time on my MacBook fine. Proceeded to install on my iMac but every time it ends with an "Install Failed - Please clean the disc"... OR "Install Failed: The installer could not copy the necessary support files". The install will run for about 5-10 minutes then gives the message. Both machines have the newest Leopard software installed. I have tried booting from disc (holding C down) but still no luck. I have tried multiple times for the past two days with no success. Any ideas?