Your Guide to Group Policy Troubleshooting

http://blogs.technet.com/b/grouppolicy/archive/2010/02/24/troubleshooting-group-policy.aspx

Why didn't my Group Policy settings apply?

http://blogs.technet.com/b/grouppolicy/archive/2009/12/17/why-didn-t-my-group-policy-settings-apply.aspx

http://technet.microsoft.com/hi-in/magazine/2007.02.troubleshooting(en-us).aspx

Troubleshooting Group Policy

http://blogs.technet.com/b/grouppolicy/archive/2010/02/24/troubleshooting-group-policy.aspx

Troubleshooting Group Policy Using Event Logs

http://technet.microsoft.com/en-us/library/cc749336(WS.10).aspx

Group Policy Center

http://technet.microsoft.com/en-us/windowsserver/bb310732.aspx