  Quantum Hall stripe (QHS) phases, predicted by the Hartree-Fock theory, are
manifested in GaAs-based two-dimensional electron gases as giant resistance
anisotropies. Here, we predict a ``hidden'' QHS phase which exhibits
\emph{isotropic} resistivity whose value, determined by the density of states
of QHS, is independent of the Landau index $N$ and is inversely proportional to
the Drude conductivity at zero magnetic field. At high enough $N$, this phase
yields to an Ando-Unemura-Coleridge-Zawadski-Sachrajda phase in which the
resistivity is proportional to $1/N$ and to the ratio of quantum and transport
lifetimes. Experimental observation of this border should allow one to find the
quantum relaxation time.
