If you restore the configuration database, data in the configuration database will not be synchronized with data in other SharePoint databases. If this data is not synchronized, users may experience various random errors.
For example, a Windows SharePoint Services 3.0 content database may contain data about a newer site. If the configuration database does not contain information about this site, the site is orphaned.
In order to restore the configuration database, you have to use manual steps. You cannot use the built-in backup and restore functionality. This guidance is provided in documentation on the following Microsoft TechNet Web sites: