I've seen this at my father's house. He used to keep his old 17" monitor set to 800 X 600 resolution (Macular Degeneration has taken it's toll on his eyesight).
Very often he'd have to agree to something and the screen simply wouldn't extend far enough down for him to do it.
I showed him how to increase the resolution and suddenly he could scroll further down.
I don't know what your display settings are so this may or may not apply, but try increasing the resolution.
I also read that if you hit the Tab key three times and press Enter, it will accept the agreement even if you cannot see it.