Stick-slip dynamics of polymer liquids sheared between aluminum, stainless steel, and a-brass substrates are investigated using model 1,4-polybutadiene (PBD) melts with abroad range of molecular weights 6.7 x 10(4) less than or equal to M-n less than or equal to 5.15 x 10(5). A variable gap, 50 mum less than or equal to H less than or equal to 750 mum, planar-Couette shear flow apparatus equipped with a centrally mounted shear force transducer is used to produce uniform steady shear flow in the polymers and to measure shear stresses over a constant area near the shear platen's center. The same instrument is used to quantify extrapolation lengths b from steady shear flow measurements at multiple gaps. Experiments performed using aluminum (Al) and stainless steel substrates reveal dramatic transitions from simple shear flow to stick-slip dominated flows at shear stresses near a critical value (sigma* - 0.26 +/- 0.02 MPa. The stick-slip regime is evidenced by asymmetric transient stress oscillations that at first observation possess periods close to the longest relaxation times of polymers studied. At higher shear rates, stress oscillations become more pronounced and their frequency increases nearly in proportion to the applied shear rate. At even higher rates, the oscillations disappear altogether and are replaced by constant, steady-state shear stresses that are substantially lower than those observed prior to the onset of the stick-slip flow regime. Several features of the stick-slip transition, including complete reversibility of the effect and a nearly quadratic dependence of extrapolation length on polymer molecular weight, appear consistent with expectations for apparent slip by flow-induced disentanglement of surface adsorbed and bulk polymer molecules. Planar-Couette flow experiments performed using polished alpha-brass substrates reveal very different physics, however. These experiments, for example, show no evidence of the stick-slip transition observed with Al and stainless steel; they in fact yield steady-state shear stresses that are consistently about 2 orders of magnitude lower, and with no noticeable oscillatory character. Oxidation of the a-brass substrates at elevated temperatures dramatically increases steady-state shear stresses and yields transient stresses that bear a weak signature of the stick-slip process. Both sets of results are discussed in terms of interfacial slip mechanisms for polymer liquids at fluid/solid boundaries.