Group Policy Preference Power Plan "Blocked By Group Policy"

I noticed this error in the application event log of a Windows 7 PC:

Log Name:      Application
Source:        Group Policy Power Options
Date:          3/21/2013 3:19:42 AM
Event ID:      4098
Task Category: (2)
Level:         Warning
Keywords:      Classic
User:          SYSTEM
Computer:      xxx
Description:
The computer 'Power Plan (Windows Vista and later)' preference item in the 'Windows 7 Desktop Power Plan {A078F08F-45CC-4209-A264-FE0CB5635A99}' Group Policy object did not apply because it failed with error code '0x800704ec This program is blocked by group policy. For more information, contact your system administrator.' This error was suppressed.
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="Group Policy Power Options" />
    <EventID Qualifiers="34305">4098</EventID>
    <Level>3</Level>
    <Task>2</Task>
    <Keywords>0x80000000000000</Keywords>
    <TimeCreated SystemTime="2013-03-21T10:19:42.000000000Z" />
    <EventRecordID>7687</EventRecordID>
    <Channel>Application</Channel>
    <Computer>xx</Computer>
    <Security UserID="S-1-5-18" />
  </System>
  <EventData>
    <Data>computer</Data>
    <Data>Power Plan (Windows Vista and later)</Data>
    <Data>Windows 7 Desktop Power Plan {A078F08F-45CC-4209-A264-FE0CB5635A99}</Data>
    <Data>0x800704ec This program is blocked by group policy. For more information, contact your system administrator.</Data>
  </EventData>
</Event>

How can I find out exactly why it is not working?  "Blocked by group policy" is not specific enough.