my friend's iTunes started to randomly crash yesterday. so to solve that problem, he uninstalled iTunes (also deleted the Library files), and now he can't seem to reinstall it. when he opens the package (iTunes.mpkg), a window pops up that says "you cannot continue, there is nothing to install." and when he custom installs it, it skips every installation process. help, please? we've tried Googling and searching the Apple support database but we couldn't find anything.