Abstract: The role of surface-induced modifications can be critical to understanding the properties of nanomatcrials, and may be probed experimentally with an external magnetic field. In typical metals, this gives rise to a small (one percent) magneto-resistance, with a contribution from quantum-mechanical weak localization at low temperatures. In this work, however, we demonstrate a giant (as much as 150 percent) and strongly hysteretic magneto-resistance in nominally non-ferromagnetic silicide films and nanowires. The magnitude of the magneto-resistance and hysteretic behavior show a strong dependence not only on the magnitude of magnetic field, but also on the field-sweep rate. This anomalous magneto-resistance also shows strong temperature dependence and is quenched above a few Kelvin, where conventional disordered-transport behavior due to weak-antiloealization is recovered. The dynamic characteristics of this effect, which resembles the butterfly hysteresis exhibited by systems of weakly-interacting molecular magnets, are suggestive of weakly-interacting localized paramagnetic moments that form at the surface oxide of the silicide nanostructure or at the interface between silicide and silicon substrate. The source of these localized moments is thought to be the dangling bonds that arise in this region, and the large magneto-resistance is presumed to result from the interaction of conducting electrons with localized dangling bond spins. The data suggest that this interaction can have dramatic consequences for transport when the system size is reduced to the nalioscale in one or more dimensions.