If you're using ZTP, BizTalk, or anything that uses Enterprise Services (COM+), after installing Windows Server 2003 SP1, you need to install the post-SP1 hotfix listed in 896729.

http://support.microsoft.com/?id=896729

From the article:

  • Provide extended COM+ services to support the Indigo Microsoft .NET technologies for building and running connected systems through advanced Web services.
  • Provide support for the Indigo WS-AtomicTransaction specification in the Distributed Transaction Coordinator (DTC).
  • The DTC stops responding (hangs) or leaks memory when the DTC is used with Microsoft BizTalk Server 2004.
  • You experience slow performance when there are available threads in the thread pool. This issue occurs even when you configure the COM+ single-threaded apartment (STA) thread pool with the EmulateMTSBehavior registry key.