I think what's happened is you changed something so that the page looks ok on your particular monitor, but it isn't taking into account the resolution on your users' monitors. I tried changing my screen resolution a little, and it has helped (a little). It still isn't right though.

My monitor is more square and not a widescreen display like you may have. What I see actually cuts off the right side of my posts. Changing the resolution helped that a tiny bit. But I can't change the resolution enough to make it totally viewable.

The fact that everyone has a different type and size monitor makes it more complex for you to do it right, I would guess.