Yes, Ernie, you can over-knead dough. An over-kneaded dough is soft and sticky and no longer able to be stretched, much like worn-out elastic. In yeast bread making, gases produced during fermentation of sugars and starches are trapped within the dough. A well- kneaded dough has developed an elastic network of gluten strands that stretch and expand allowing the dough to raise. An over-kneaded dough cannot stretch; dough will not raise. If you have a very strong hand, you could easily over-knead your dough. In hand kneading, when dough is smooth and little bubbles are visible beneath the surface, it is time to stop. When using a heavy-duty mixer with a dough hook(s), knead for a maximum of 5 to 7 minutes until dough ball is smooth and elastic. Another check is to pinch off a small ball of dough. Hold the dough with both hands between the thumb and forefinger and begin stretching it out, much like stretching a balloon before blowing it up. When the dough is kneaded enough, it will not tear easily and a translucent membrane will be visible. This is called a gluten window.