Jane has a three year old MacBook running Snow Leopard, and CDs she gets from her doctors won't run on it. Leo says that Jane should make sure it's a CD, not a DVD. It may be that her drive doesn't support DVDs, just CDs. Leo says that the program needed was called "Rosetta," and that's an old emulator program designed to run older, proprietary software. Leo says Jane doesn't want to install that because OSX has moved beyond it. Leo recommends asking the doctor to install a program that works with modern Macs.