INTRODUCTION This article discusses the Change Analysis Diagnostic tool for Microsoft Windows XP. This tool provides an easy way to track changes to certain parts of the operating system. The tool lets support professionals better understand the modifications to users' computers that may have caused problems. Support professionals can then suggest troubleshooting steps. MORE INFORMATION As computer programs grow more complex, extensible, and connected, users have more trouble understanding what makes their computers behave differently. Network connectivity lets computers download programs automatically. Then, the computers can install the programs automatically. Because of browser extensibility, components can be added to the browser in sophisticated ways that change the browsing experience. Users cannot always understand the programs and their interactions. Therefore, troubleshooting can be a very difficult task. The Change Analysis Diagnostic tool is especially helpful because of the following issues: