  Given a DT-operator $Z$ whose Brown measure is radially symmetric and has a
certain concentration property, it is shown that $Z$ is not spectral in the
sense of Dunford. This is accomplished by showing that the angles between
certain complementary Haagerup-Schultz projections of $Z$ are zero. New
estimates on norms and traces of powers of algebra-valued circular operators
over commutative C$^*$-algebras are also proved.
