In order to fix the issue, I suggest you to delete the installation package and download a new one from the official web page. Click the red Download button, save the file to your computer and install it following the self-explained steps. If it doesn't work and you're using Windows XP or below, try updating Windows Installer using the link provided by Microsoft. If you're using Windows Vista or above, update it through Windows Update. Also, make sure you're logged on an Administrator account and all third party firewalls are temporarily disabled.
