Rollback actions and the REDO logs

Hi,

We have a situation where - on an infrequent basis - a change to a record in the database appears to have rolled back; i.e.: a surname changes from 'Smith' to 'Jones', and we have the originating event (form submission) logged.  However, the change does not 'stick' and the original data persists as a result.  These events are rare but they do seem to be genuine cases of original -> changed -> rollback(?) -> original.  If there is indeed a rollback occurring then it should be in the REDO log if I have my facts straight. So, assuming the facts