This issue may occur in a scenario in which you did not add the Windows Vista image at the time that you configured Windows Deployment Services (WDS) on the Windows Server 2003-based computer.
When you configure WDS, you are prompted to add images to the WDS server. If you plan to add a Windows Vista image, you have to point to the Sources\boot.wim file that is located on the Windows Vista DVD.
But if you decide not to add a Windows Vista image, the WDS server is already configured to use the PXEBoot.com file instead of the Startrom.com file to start a PXE client session. Therefore, the WDS server searches for the PXEBoot.com file in the following folder:
remoteinstall\boot\x86
If the WDS server cannot find the PXEBoot.com file in this folder, you receive the error message that is mentioned in the "Symptoms" section when you start a PXE client session.