You must add the identity of the application pool to the IIS_WPG, SPS_WPG, and STS_WPG local groups on all servers in the server farm. These groups have specific permissions on IIS, SharePoint Portal Server, and Microsoft Windows SharePoint Services private data. Failure to add the application pool identity to these groups causes the portal site or sites using that application pool to be nonoperational.

1. On the taskbar, click Start, point to Administrative Tools, and then click Computer Management.
2. In the console tree, under the System Tools node, expand the Local Users and Groups node.
3. Click Groups.
4. For the IIS_WPG, SPS_WPG, and STS_WPG groups, do the following:
   1. In the details pane, double-click the group.
   2. In the properties dialog box that appears, click Add.
   3. In the Select Users, Computers, or Groups dialog box, add the account that you specified as the identity for the application pool, and then click OK twice.