1. Restart the computer. This may clear any internal software issues, caused by a faulty memory cache in the computer's hardware. Click the 'Start' menu in the lower left-hand corner. Select 'Restart.'
2. Log in as an administrator on the computer where you wish to install the iTunes software. Administrator privileges are required to install iTunes on Windows. The administrator account is always listed first on the Windows log-in screen. If you are not the administrator or owner of the computer, contact the individual who is and ask if she will sign in for you.

3. Ensure you have the most recent Windows updates downloaded and installed from the Microsoft Update website (see link in Resources). Microsoft regularly releases software patches and updates that may resolve issues you may encounter when attempting to install software such as iTunes.
4. Completely uninstall previous version of iTunes if you have have ever previously operated iTunes on your computer. If this is your first time installing iTunes, go to Step 5. Click the Start menu and select 'Control Panel.' Click 'Add or Remove Programs' (Windows XP) or 'Uninstall A Program' (Windows Vista). Click the 'iTunes' program in the dialog window that appears. Restart your computer after you have uninstalled previous version of iTunes.
5. Clean up the iTunes Windows Installer Package. Launch Internet Explorer and visit the Microsoft Windows Installer Clean-Up Utility webpage (see link in Resources). This program will clean up system files that can create software conflicts with the iTunes Windows Installer Package. Click the link that reads 'Download the Windows Installer Cleanup Utility package now,' next to the download icon. Double-click the utility icon after you've downloaded it from the Microsoft website. Follow the on-screen instructions to complete the automated software installation. Click 'Start' and select 'All Programs.' Click 'Windows Install Cleanup.' Select 'iTunes' in the utility's screen. Click 'Remove.' Click 'Exit' after the utility has finished cleaning up the installer package. Restart your computer.