Microsoft Knowledge Base Article 216359 contains the following summary:
When you are troubleshooting the application of a group policy, it may be necessary to validate that the appropriate objects are
in the Active Directory and that the file structure is correct in SYSVOL on each domain controller on which the Group Policy Object
(GPO) is replicated.
A key piece of information in this process is the Globally Unique Identifier (GUID) associated with the GPO. This article discusses identifying a GPO with its GUID.