new topic comments problem

when I enter comments or post new topic. The box that I type in will not allow me to see what I am writing if I get further down the comment box.
The little slider bar to the right keeps jumping up to the top of the comment box. if that makes sense to anyone? feels like the page up key is been pressed all the time. (it's not).

Turn on "compatibility mode" or use Firefox.

Thanks, will try it.