Ria:

I have that problem before in NWS and always was that I was creating a select statement and brake the conection and left the table lock. The SQL always try to open the table exclusive so you need to open the table first in share mode before issue the SQL.

Also if you going to append that log file simultaneusly I recomend you to use VIEWS instead of appends. Let me know what method you are using to append those record. Views, Insert SQL, Appends with rlock or flock?