Here are some links to help you diagnose problems.

You may have to start and run a long term performance log to see if it can track down an issue.

Hopefully something here helps you to track down the issue.

Microsoft ® Windows Server ™ 2003 Performance Advisor
http://www.microsoft.com/downloads/...6b9-a9a5-9bffcd237da2&DisplayLang=en

Windows Server 2003 Performance Counters Reference
http://technet2.microsoft.com/Windo...4f52-a9f8-09d5ebeb9ef21033.mspx?mfr=true

Introduction to Windows Support Tools
http://technet2.microsoft.com/Windo...4623-98ab-dc26f1faa6eb1033.mspx?mfr=true

Windows Server 2003 Service Pack 1 Administration Tools Pack
http://www.microsoft.com/downloads/...36A-A392-25793A25BAD7&displaylang=en

Windows Server 2003 Resource Kit Tools
http://www.microsoft.com/downloads/...AE7-96EE-B18C4790CFFD&displaylang=en

Windows Server 2003 Service Pack 1 32-bit Support Tools
http://www.microsoft.com/downloads/...E81-B3BE-4E7AC4F0912D&displaylang=en

Internet Information Services (IIS) 6.0 Resource Kit Tools
http://www.microsoft.com/downloads/...C73-B628-ADE629C89499&displaylang=en