First, right-click on the Taskbar - point to Toolbar and uncheck all the
Toolbars listed. Now, try to reduce the size of your Taskbar. If you get
success that means the problem is with the "Handlers".
Again Right-click on the Taskbar and check the Toolbar you uncheck in
previous step and your Taskbar may increase in size again. Notice the Handler
in down line of your Taskbar. Drag and drop that Handler to Top bar or near
the Toolbar icons.