Comment 2 for bug 1172863

There's a partial solution to this: "slide" the Unity launcher icons up, and let go. Here are the steps:
1. Move your mouse to the launcher icons area (it can either be on one of the icons or in an empty area)
2. Hold down your mouse button and move up or down. Don't hold down too long without first moving the mouse; otherwise, you'll be moving one of the icons.
3. Let go.

This works for me, but I have to do this every time I start my computer.