Oracle does allow you to DELETE from views, but then it puts restrictions on that (which I think you'd need to be an Oracle guru to understand...some are really weird!).
Is it possible that is what is happening here? That you think you are deleting from a table but it's really from a VIEW of a table?
An optimist sees the glass as half full.
A pessimist sees the glass as half empty.
A realist drinks it no matter how much there is.