If using active (not instant) yeast, put the yeast in the warm water and let sit for 10-15 minutes to become bubbly. If using instant yeast just add to the water and continue.
Stir in potatoes, sugar, oil (or butter) and salt. Mix well.
Mix in flour to make a soft -- not sticky -- dough. Knead for 5-8 minutes.
Place in a lightly oiled bowl, cover, and let rise for 1 hour or until doubled.
Punch down, divide in half, and form into logs.
Grease two 8.5"x4.5" (aka "1-pound") loaf pans.
Place logs into loaf pans, cover with oiled plastic wrap, and let rise in a warm place until doubled, 45-60 minutes.
Heat oven to 350°F
Make a slash down the center or a couple of diagonal slashes for venting.
Bake 35-40 minutes or until lightly browned. Let rest in pan for 5-10 minutes before removing to a wire rack to cool completely.