locks..

Hi guys
I am being faced with a persistent lock problem.. I am trying to insert
a single row in the exhibits table.. While using the psql interface the
following debug lines are getting generated..

query: insert into exhibits(exhibit_id,created_by,title,description,artist_id1,artist_id2) values (605,1001,'whats happening',null,2,157);
ProcessQuery
query: SELECT oid FROM "artists" WHERE "artist_id" = $1 FOR UPDATE OF "artists"
query: SELECT oid FROM "artists" WHERE "artist_id" = $1 FOR UPDATE OF "artists"
query: SELECT oid FROM "atoday_users" WHERE "user_id" = $1 FOR UPDATE OF "atoday_users"
CommitTransactionCommand

HOwever when i use my web application (jdbc) i get the first 2 debug
lines and not the third.. This wasnt happening till now.. What could be
the reason.. The table is locked after this operation and all other
inserts fails either thru the web interface or the psql interface..

query: insert into exhibits(exhibit_id,created_by,title,description,artist_id1,artist_id2) values (606,1001,'hello',null,2,196)
ProcessQuery
query: SELECT oid FROM "artists" WHERE "artist_id" = $1 FOR UPDATE OF "artists"
query: SELECT oid FROM "artists" WHERE "artist_id" = $1 FOR UPDATE OF "artists"

Can any one help me out with this.. Restaring the database is not
helping..

Postgres Server 7.0.2
Thanks
Anand