After restoring a backup of my database, I keep getting unable to login to database errors?

1. Using SQL Server Authentication

USE SpiraTeam
GO
EXEC sp_change_users_login 'Update_One', 'SpiraTeam', 'SpiraTeam'
GO

2. Using Windows Authentication on Windows 2003/2008/Vista/7

USE SpiraTeam
GO
ALTER USER SpiraTeam WITH LOGIN = [NT AUTHORITY\NETWORK SERVICE]
GO

3. Using Windows Authentication on Windows XP

USE SpiraTeam
GO
ALTER USER SpiraTeam WITH LOGIN = [MACHINENAME\ASPNET]
GO

The example above was written with SpiraTeam in mind, since it uses the database name 'SpiraTeam'. If you are experiencing the same issue with SpiraTest, SpiraPlan or KronoDesk, please substitute the name in the SQL commands accordingly.