  We study here the onset of charge density wave instabilities in quantum Hall
systems at finite temperature for Landau level filling $\nu>4$. Specific
emphasis is placed on the role of disorder as well as an in-plane magnetic
field. Beyond some critical value, disorder is observed to suppress the charge
density wave melting temperature to zero. In addition, we find that a
transition from perpendicular to parallel stripes (relative to the in-plane
magnetic field) exists when the electron gas thickness exceeds $\approx 60$\AA.
The perpendicular alignment of the stripes is in agreement with the
experimental finding that the easy conduction direction is perpendicular to the
in-plane field.
