Let's see if manually downloading the iTunes 64-bit installer resolves this issue. Please uninstall iTunes completely, by using this information:
Important: Uninstalling these components in a different order, or only uninstalling some of these components may have unintended effects.
Once completely removed, download iTunes 11.0.2 for Windows 64 from this page:
Also, you may want to make sure your computer meets the minimum system requirements outlined on this page.