Nonequilibrium molecular dynamics simulations are carried out for a liquid undergoing shear flow. Upon cooling at constant shear rate, the temperature dependence of the viscosity changes from faster-than-Arrhenius to Arrhenius: this change is analogous to a fragile-to-strong transition. An energy landscape analysis shows that this change in the temperature dependence of the viscosity occurs because the region of the energy landscape visited by the system becomes nearly temperature-independent. (C) 2003 American Institute of Physics.