Windows Management Instrumentation (WMI) is an essential component in Windows as most of the built-in tools in Windows XP are based in WMI scripts. For example, some of the pages in the Help and Support Center, System Information and other tools use WMI.

If you encounter any problems with WMI, or unable to run any WMI based script, it can be due to several reasons including a corrupted WMI repository, missing WBEM modules, incorrect DCOM permissions. Finally there is a single tool that can detect all the problems and generates a detailed report for you.

WMIDiag.vbs is a VBScript script designed to help you ascertain the current state of the WMI service on a computer. The download package includes the utility itself, a ReadMe file that discusses how the tool works (and how to best use it), and sample spreadsheets that provide information about the default WMI configuration on various versions of the Microsoft Windows operating system.

Download details: The WMI Diagnosis Utility

I've provided a brief introduction about WMIDiag in this page as well.