I've run into this issue before. When setting up a MBP after a fresh install of Leopard or Snow Leopard, I usually choose to transfer files and setting from Time Machine. But whenever I do this, iTunes suddenly can no longer "find" most of my songs, even though they are in the iTunes folder, and I have to spend days telling iTunes where to find each of the missing tracks. What could be causing this, and how do I fix it? Already tried permissions fixing and uninstalling/reinstalling iTunes.