  We have measured the magnetoresistance of a very low density and an extremely
high quality two-dimensional hole system. With increasing magnetic field
applied perpendicularly to the sample we observe the sequence of insulating,
$\nu=1/3$ fractional quantum Hall liquid, and insulating phases. In both of the
insulating phases in the vicinity of the $\nu=1/3$ filling the
magnetoresistance has an unexpected oscillatory behavior with the magnetic
field. These oscillations are not of the Shubnikov-de Haas type and cannot be
explained by spin effects. They are most likely the consequence of the
formation of a new electronic phase which is intermediate between the
correlated Hall liquid and a disorder pinned solid.
