I have noticed the following phenomenon when editing email messages before sending out. If I want to make a correction by deleting a letter I have to press the delete key twice. To do it by backspacing only needs one press. This started at some point in the past which I can't remember, and is very irritating as one often fails to notice and the word then has the correct and incorrect letter in it. Any ideas on how to stop this and go back to one-key deletion?