I am using Windows 7 on 64bit machine
When I allow it to install updates. It seems to be working OK (i.e) it downloads but when it is installing it looks for file iTunes 64.mis
Step 3: In your Start menu click All Programs and then click Windows Install Clean Up. The Windows Installer CleanUp utility window appears, listing software that is currently installed on your computer.
Step 4: In the list of programs that appears in CleanUp, select all iTunes entries and click "Remove", as per the following screenshot: