Taskbar "Use Small Icons" Disabled

I want to select this option of my taskbar to make it smaller like Vista but for some weird reason it is grayed out and unable to be changed. Can anyone explain why and/or how to do it from the registry?

Thanks to any response.

Hello Scouser, and welcome to Seven Forums.

Here you go mate. OPTION TWO in the tutorial below just added.

http://www.sevenforums.com/tutorials/741-taskbar-use-small-large-icons.html

Hope this helps,
Shawn