Every now and then our transaction fails with "ORA-01031 Insufficient privileges" error. The detail error message shows that the insert statement is what we expect it to be and the database connection is also correct. The privileges are set up correctly, i.e. the db user in question does have insert grants on the table.
Under normal circumstances the transaction succeeds. The failure occurs roughly once every 10000 transactions.
We are running Oracle 10G on Solaris.