What causes the error, "There are database users in the current database which are not linked to any SQL Server logins"?
The complete error "There are database users in the current database which are not linked to any SQL Server logins. Please make sure that all orphaned DB users are fixed before starting the server" indicates a corruption in the SQL Server login and as such does not allow the user to log on to that instance. Such a user is said to be an orphaned user of the database on that server instance. A database user can become orphaned if the corresponding SQL Server user name is dropped. Most likely, a database user becomes orphaned after a database is restored or attached to a different instance of SQL Server. Orphaning can occur if the database user is mapped to a SID that is not present in the new server instance.
Use SQL Server Management Studio or any other tool that executes SQL statements to How to address Orphaned Users after upgrading to StarTeam 2009..