I don't have any suggested fixes to offer, but I am curious about how many people seem to be encountering issues with installing or upgrading the most recent versions of iTunes. Has anyone been able to suggest a common cause? I ask because although I have five installations of iTunes (and effectively manage three others for family members), using different versions of Windows (XP, Vista, 7, 8.1), wildly different hardware configurations, three different anti-virus products ... I've never seen any of the issues that many users are reporting. Indeed, the only problem I ever see is that the Apple Updater occasionally times out when downloading a new version of iTunes, which I can always address by downloading the full installer from Apple's website.