Say user 1 and user 2 belongs to CRM organizations - Org1 and Org2. When user 1 tries to access CRM application through web client, it takes him to Org1. When user 2 tries to access CRM application through web client, it takes him to Org2. Reason being, the CRM Organization which is rendered when the users hit the CRM website depends on the sequence in which they were added to the Organizations. Please see the explanation below:

If user 1 is added to Org1 and then added to Org2, when this user tries to access CRM, it will render Org1 and not Org2. Similarly if user 1 is added to Org2 and then to Org1, when this user tries to access CRM, it will render Org2 and not Org1

Because of this Default Org Behavior in Dynamics CRM if an Org is Disabled and we have multiple Organizations into the CRM Deployment. Connection form Plugin registration tools, Scribe and E-mail router always goes to the org in which the user has been created first irrespective of that org is enabled Or Disabled.

Error in the CRM server platform trace-
Cannot open database "CCBCRM_EMEA_MSCRM" requested by the login. The login failed.
>Login failed for user 'NAM\SYS_NAM_MSCRM_PROD'.> at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning()
> at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj)
> at System.Data.SqlClient.SqlInternalConnectionTds.CompleteLogin(Boolean enlistOK)
> at System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(ServerInfo serverInfo, String newPassword, Boolean redirectedUserInstance, SqlConnection owningObject, SqlConnectionString connectionOptions, TimeoutTimer timeout)