Something about the scrolling is messed up when a large post is being typed up. Need bunch of text typed to see it, can't duplicate with blank lines.
Seems to have something to do with the scroll bar - one needs to over and drag it down, as if it is not keeping up with the carriage returns or something.
I just saw retrolefty's post about IE8 compatibility, I'll try that (changed under Tools) to see it if makes a difference.
Seems to help ...