Most of the times its located in :
If it needs shrinking do the following :-
Backup the database using SQL Management. Connect to the instance using
as the server name.
Once backed up right click on the Database Sharepoint Config and click new query.
Execute each of the following querys in turn
BACKUP LOG [Sharepoint_Config_blahblahblah] TO DISK='D:\temp\configLogBackup.bak' GO
BACKUP LOG [Sharepoint_Config_blahblahblah] WITH TRUNCATE_ONLY USE [Sharepoint_Config_blahblahblah] GO
DBCC SHRINKFILE (N'Sharepoint_Config_blahblahblah_log' , 50) GO