I'm getting the following error within ZCM for a Windows Group Policy that is applying to Windows XP SP3 machines:

Full Message: There was an error while accessing content for policy "Non-Volatile User Package-XP-Windows Group Policy". The error was - "Path for the group policy content is null."
Additional Information: Path for the group policy content is null.
Severity: Error
Date: April 9, 2009 1:51:02 PM
Acknowledged Date: None
Source: /Devices/Workstations/<workstation name>
Message ID: POLICYHANDLERS.WinGPPolicy.ContentError
Probable Cause URL: None
Log ID: 5cb1763b9421ee1b264c1aae7322d6df
Related Objects: /Policies/101/Users/Non-Volatile User Package-XP-Windows Group Policy

However, when I look at the device's Zenworks Agent it reports the effective policy as "success".