I've seen this twice now, the differences are very small so read the error message carefully:
Unable to cast:
The current build operation (build key Build Key[Microsoft.Practices.EnterpriseLibrary.Data.Database, LSBC]) failed: Unable to cast object of type 'Microsoft.Practices.EnterpriseLibrary.Data.Configuration.DatabaseSettings' to type 'Microsoft.Practices.EnterpriseLibrary.Data.Configuration.DatabaseSettings'. (Strategy type ConfiguredObjectStrategy, index 2)
Type initializer failed:
The current build operation (build key Build Key[Microsoft.Practices.EnterpriseLibrary.Data.Database, LSBC]) failed: The type initializer for 'Microsoft.Practices.EnterpriseLibrary.Data.Database' threw an exception. (Strategy type ConfiguredObjectStrategy, index 2)