First time I ever saw this happen.
This morning when booting up, got a popup notice that an Adobe Flash Player update was available. Went to the System Restore to create a restore point, as never trust any download. Started typing “before download…” and got "bemore…). WTF?
Closed this, opened Word and tried all the keys. Only the “f” key gave a wrong letter, the “m.” Spent special attention to be sure was not hitting the wrong key.
Without further ado, invoked the universal MS panacea: rebooted. Everything then OK.
What in the world would have caused this one key to suddenly decided it wanted to be an m? I am sure I did not drop a M & M into the keyboard.