  Near the end of 2001 February, the black-hole candidate (BHC) GRS 1758-258
made an abrupt transition from a standard hard (low) state to a soft state.
Unlike Cyg X-1 and other BHCs, whose luminosity increases during this
transition, GRS 1758-258 was dimmer after the transition. We present
observations with the Proportional Counter Array on the Rossi X-ray Timing
Explorer and interpret the phenomenon in the context of a ``dynamical'' soft
state model. Using this model we predicted that mass transfer from the
companion had ceased, and that the luminosity should decay on a timescale of a
few weeks. The most recent data support this prediction, being consistent with
a decay time of 34 dy. The current state is consistent with the ``off'' state
of GRS 1758-258 reported by GRANAT/Sigma in 1991-1992.
