I had a bad problem with a calculus professor too... It was a combination of several factors; He was about 70, a German who had been living in Argentina like FOREVER so you can only imaging the accent when he was speaking English, he mumbled in the way that really old people do, and when he was writing out equations on the overhead projector his handwriting was so bad as to be totally illegible.. he should have just handed things over to his TA.