sqlldr running slow after indexes created

let me explain this….

I had running 1 session of sqlldr while I run indexes into table for 6 fields… now the indexes are completed but the sqlldr running very slow it load one file after each 30 minute…

now when I do any alter to set the indexes off it won’t let me do it and though an error of ( ORA-000054 and ORA-000604) even if I run another sqlldr….

any suggestion will be highly appreciate…. bellow is sample of my control files header…

OPTIONS(DIRECT=TRUE,ROWS=10000,BINDSIZE=209700000,readsize=209700000) 
load data 
append 
into table name 
FIELDS TERMINATED by '!' 
OPTIONALLY ENCLOSED by '"' 
trailing nullcols 

When I run following query

select * from dba_dml_locks

session_id,owner,name,mode_held,mode_requested,last_convert,blocking_others 
123,username,tablename,exclusive,none,1228,not blocking 

any suggestion … this is my daily scheduler to load around 8000+ files around 20GB so any suggestion