What does it say about my keystrokes that the letters M and N on my computer keyboard are disappearing? No other letters seem to be affected. I’d expect this kind of behavior from S, T and the vowels, but M and N? N is in particularly bad shape; I can barely make out the letter. Do I replace the keyboard and help clog a landfill? Re-letter the keys with white paint? No matter what I do, the board won’t look the same. Then again, maybe I can just count on my memory to make sure these two letters aren’t forgotten.