  The parallel magnetic field tuned two-dimensional superconductor-insulator
transition has been investigated in ultrathin films of amorphous Bi. The
resistance is found to be independent of temperature on both sides of the
transition below approximately 120 mK. Several observations suggest that this
regime is not intrinsically "metallic" but results from the failure of the
films' electrons to cool. The onset of this temperature-independent regime can
be moved to higher temperatures by either increasing the measuring current or
the level of electromagnetic noise. Temperature scaling is successful above 120
mK. Electric field scaling can be mapped onto temperature scaling by relating
the electric fields to elevated electron temperatures. These results cast doubt
on the existence of an intrinsic metallic regime and on the independent
determination of the correlation length and dynamical critical exponents
obtained by combining the results of electric field and temperature scaling.
