My computer (Dell Inspiron 600m laptop) seems to have a macro that I did not install. When I am typing either in MS Word or AOL write modes and I hit the letter "b" my typing jumps to wherever the cursor is. I do not know how to undo this macro. Any suggestion?

I don't know what would cause that unless you are inadvertently hitting something other than b to cause that.

I wonder whether the letter b has been inadvertently assigned as a keyboard shortcut? Unfortunately, if it has, I've forgotten how to undo it - maybe someone else knows?

   No, the B key alone cannot be assigned to a macro (it has to be a combination of keys, like, B, Alt, and Ctrl).
   I still think that you are inadvertently hitting the touchpad or something else.  You might try covering the touchpad up with stiff paper or cardboard.

Many Dell Laptops have both a "Mouse Pad" and a "Joystick" controller.  The Joystick controller sometimes called an "eraser nub" can be used to control mouse functions.  It is located on the keyboard in the upper half of the "B" or "b" key.  Maybe this controller is stuck or sticking to the "b" key (either mechanically or electronically).  This might cause the curser or control point to "jump".

GaryIII