Roaming Profile – Security Issues

I have Windows Server 2003 R2 Enterprise Edition, I create Users in an Organizational Unit and deploy the OU in GPO, I tried to create the user profile as a roaming profile, and XP Sp2 is my client machines, now i got the error message while try to create roaming profile “Windows cannot update your roaming profile. Possible causes of this error include network problems or insufficient security rights. If this problem persists, contact your network administrator.”

Please give the exact solution