Well.. it's not that.. it's just that once I hit the bottom of the post window, the scroll bar completely goes berzerk.  If I hit enter a bunch of times to space things out, I'll hit the bottom of the window, and it won't let me type further down.  I'll try it here..
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k, can still type here ok
still working
HERE->it dies on this line, the window will not let me scroll below this line while I'm typing.  Once I hit this particular line, anything I type immediately gets pushed below the bottom of the window.  I can drag it there manually and scroll just fine, but as soon as I hit a key, it pushes this line below the typing space.  It happens to whichever line I happen to type on.  
if I hit enter again, it goes back up to above the previous line.  The Only time I can see what I'm typing is while a key is pressed, meaning the scroll bar snaps to the letter I've typed as I'm typing it, then immediately snaps back up to the line above.  Essentially, the window is jumping up and down every time I press and release a key, and it makes it completely impossible to read what I'm typing.
Also, past that point I cannot scroll the cursor down manually with the arrow keys.  They stop working correctly, and you get stuck at that line I indicated.
Oh, highlighting text below that line is out as well, I can't drag the cursor without it snapping up above that line. 
Same thing happens when I try and edit the post.
It's not that it makes it impossible to post... but I have to post in snippets so I don't hit the limit.