Quantization Failure in Unified Field Theories
  Studies of geometrical theories suggest that fundmental problems of quantization arise from the disparate usage of displacement operators. These may be the source of a concealed inconsistency in the accepted formalism of quantum physics. General relativity and related theories cannot be quantized by the classical procedure. It is necessary to avoid the construction of differential equations by operators applied algebraically. For such theories, Von Neumann's theorem concerning hidden variables is avoided. A specified alternative class of gravitational-quantum-electrodynamic theories is possible. 
Daniel C. Galehouse