Win32.OpenInstall is a threat detected by either Microsoft Security Essentials, Windows Defender for Windows 8 or Microsoft Safety Scanner. This Win32.OpenInstall threat is classified as PUP a Potentially Unwanted Program by Microsoft because it inflicts and acts as a malicious threat into your computer system. Win32.OpenInstall is not a virus but it does act like one. Win32.OpenInstall is adware which is bundled using custom installers and dropped on your computer during the installation process. Most users have no idea how this Win32.OpenInstall threat is installed on there computer and what it is, until Microsoft Security Essentials, Windows Defender for Windows 8 or Microsoft Safety Scanner detects it as a malicious threat or virus. Follow our instruction to remove this Win32.OpenInstall threat from your computer.