Quick update on this thread: my troubles are over! It seems that the problem was simply a sleepy morning and the result was very poor stropping. That's why the razor was rough and pulling. And since I have very sensitive skin (so sensitive that a light touch with a DE leaves my face all red and burnt up...) the shave was awful. But I thank you all for the replies... I learned a lot on this thread... And I learned a valuable lesson: no stropping before noon!