Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. High Quality Content by WIKIPEDIA articles! The Windows Installer CleanUp Utility (MSICUU2.exe) is a software utility for the Microsoft Windows operating system designed to solve uninstallation problems of programs that use the Windows Installer technology. It looks up registry references and files related to Windows Installer that were installed by various programs, and forcibly wipes invalid entries out. It works in all 32-bit and 64-bit versions of Microsoft Windows. The utility was first released by Microsoft in 1999 to help Windows-based computers clean up installed programs that would either refuse or pretend not to remove themselves from the add/remove programs feature in Microsoft Windows. The utility will only change registry values and files associated with the Windows Installer portion on the program. It will not remove many files from the computer and is only to be used as a last ditch attempt when dealing with a buggy program. The utility can only be run by users who are logged in as system administrators.