¬ ???
 

Yesterday, a friend knocked over my wireless keyboard & ever since, typing text on screem whther it be word, excel or here produces the ¬ symbol at the start of typing, unbidden. The key is not stuck as far as I can see, but it was one of those moments when the action of knocking it over opened a whole bunch of windows & complaints from the machine.

Please make it go away!

Apart from knocking your friend over too, I would suggest 're-installing' the keyboard if you can for starters. There is a morning's happy reading on Mr G under "random characters on wireless keyboard":)