Describes the new and improved features of Microsoft Windows Installer 4.5. The article also discusses the issues that are addressed from earlier versions of Windows Installer.

Describes how to troubleshoot problems that may occur when you install, uninstall, or upgrade a program on a Windows-based computer. This troubleshooter replaces the previous Microsoft Installer Cleanup Utility (msicu2.exe).

Explains that you receive an error message when you run the Setup program to install Office programs. This issue occurs because Windows Installer can only run one installation at a time unless it is a nested installation.