What Does It Mean When A Girl Starts Typing Then Stops?

It's likely that she's looking at something on a different tab, or perhaps she's out for a stroll or whatever. Doesn't always indicate that she has no interest in you. I'm willing to guess that it doesn't actually say all that much about you at all. It is likely due to the fact that the individual in question does not really like typing and were sidetracked by anything else that they wanted to accomplish during that time.