Well, in the customer reviews (of all places) I found out how to fix the scroll button. Turns out, like a lot of computer problems, it’s a cleaning issue. You just need to get that tiny little ball clean again.

The customer review explained that you just dampen a cotton tip (q-tip) with alcohol and give it a clean, let it dry for about 5 minutes and bingo. It worked for me, and I didn’t have any alcohol handy so I dipped my cotton tip in the baby wipes container instead. But, try at your own risk.

After a quick Google I’ve discovered there’s a few different ways you can get your scroll button clean. See the MacOSXHints forum for more info.