Today I was looking over the schedule for the rest of the term for the course I run and noticed that a couple of times seemed odd. Looking up the official calendar I found that somehow I had put the wrong times down for 3 lectures! Two of them are not a big deal but 1 error is really glaring. I am at a loss to explain how I made such a stupid mistake. It really pisses me off and I know the students will complain about it.