  We find that the sheet resistance ($R_s$) of patterned samples of ${\rm
LaAlO_3}/{\rm SrTiO_3}$ with a length scale of several microns may increase
significantly at low temperatures in connection with driving electrical
currents and applying in-plane magnetic fields. As the samples are warmed up,
$R_s$ recovers to its original value with accelerated recovery near ${\rm 70 \
K}$ and ${\rm 160 \ K}$. Concomitantly with the increase in $R_s$, the carrier
density and the mobility decrease and magnetotransport properties which may be
linked to magnetism are suppressed.
