Feeling powerless and depressed. My first class's term paper deadline just passed. 1/3 didn't turn a paper in (it is worth 20% of their grade) and of those that did turn it in, 1/5 I'll probably have to take to task for plagiarism. These are my first cases in four semesters teaching.
I know exactly how you feel. I had a bunch of plagiarizers in one class last year after having no plagiarism for years, and I always have students who just don't turn their work in - even though are often really bright, intelligent students. It is depressing to see the waste of a quarter's time and money for a bright student - and plagiarism feels like a personal slap in the face to me.
But that's the way it goes, I guess. I make my syllabus as clear as possible about plagiarism and deadlines, and tell my students at the beginning of the quarter that the syllabus is a contract both they and I are responsible for. If they don't fulfill the requirements of the contract, it's sad, but it's their problem. They may need to get burned in order to realize things need to change in their academic life.