Start Menu Is Suddenly Insanely Tall And Won't Change Back To Normal

For some reason, my start menu has suddenly become ridiculously tall, spanning the entire height of the screen. This image might give a better idea: imgur: the simple image sharer.

I have no idea how or why this happened. I tried searching for the problem, but I can't find a single thing even remotely related. My recent items count is at 0, so it's nothing to do with that. I've already tried fiddling about with the setting for that, but with no success at all. I tried a system restore to before this occurred, but this had absolutely no effect either. It's only affecting this profile, and no others (although, really, the only others are guest or temp accounts).