I often spend time debugging systems when things go wrong.  Besides the tools at http://www.microsoft.com/technet/sysinternals/default.mspx these are the others I use:

Microsoft Network Monitor 3
Network Monitor 3.0 can co-exist with older versions of Network Monitor. NM3 installs in %program files%\Microsoft Network Monitor 3.0, so there is no conflict.
http://www.microsoft.com/downloads/details.aspx?FamilyID=aa8be06d-4a6a-4b69-b861-2043b665cb53&DisplayLang=en
Debug Diagnostic Tool v1.1
The Debug Diagnostic Tool (DebugDiag) is designed to assist in troubleshooting issues such as hangs, slow performance, memory leaks or fragmentation, and crashes in any Win32 user-mode process. The tool includes additional debugging scripts focused on Internet Information Services (IIS) applications, web data access components, COM+ and related Microsoft technologies.
http://www.microsoft.com/downloads/details.aspx?FamilyID=28bd5941-c458-46f1-b24d-f60151d875a3&DisplayLang=en
The WMI Diagnosis Utility -- Version 2.0
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.
http://www.microsoft.com/downloads/details.aspx?FamilyID=d7ba3cd6-18d1-4d05-b11e-4c64192ae97d&DisplayLang=en

ttfn

David