I am trying to upgrade my Dad's mac mini to Snow Leopard and have encountered a problem. When I insert the Leopard disk I cannot get it to read the disk, the box comes up as if I have inserted a blank DVD. I have also tried inserting ilfe09 disk and have the same problem. Anyone any ideas???The drive does appear to be making an odd bleaping. I have tried resetting the PRAM and cannot get it to bleap??? Thanks in advance.