Getting Error Permission denied for <moz-safe-about:blank> to get property XPCComponents.utils

Hi All,

   Following is the code i am triggering from JavaScript in FF browser

netscape.security.PrivilegeManager.enablePrivilege('UniversalXPConnect');
Components.utils.import('resource://mozmill/modules/mozmill.js',
mozmill);

   I had also set the flag
"signed.applets.codebase_principal_support;true" in about:confid. But
still i am getting the error

Getting Error Permission denied for <moz-safe-about:blank> to get
property XPCComponents.utils

Can any one help?