Dark stripes on surfaces in V-Ray when rendering to texture (baking)
Solved.  The issue was with V-Ray's global ambient occlusion on the GI tab.  Once that was shut off everything renders fine.  Interestingly, V-RayDirt maps in materials seem to be behaving just fine.

UPDATE: It appears the real root problem is deeper.  This turned out to be caused by units being set to fractions instead of decimals.  This can cause some values that are very small to round off to zero as the system tries to make it a fraction.  In v-ray lights, the shadow bias was getting rounded to zero automatically in some cases.  A zero shadow bias can produce strange results in some cases.  SOLUTION: stop using fractional units and go through and fix lights with zero bias.