Keyboard expert needed?

This is a problem which has been haunting me for a long time. When filling in a post for a forum I somehow hit something on the right sde of the keyboard which deletes the whole thing irretrievably. It always happens when I really get going and have laid down some stuff--then bingo! It is snatched from me and I seldom have the patience to reproduce it. It makes me very paranoid. I have not bee able to reproduce it by hitting any keys. Does anyone know what I am doing? It would give me great peace of mind to be immune from this.