What happened to the taskbar?

Hello!
I installed the DesktopX program by Stardock. When you apply a DesktopX theme, the taskbar gets hidden. However, when I disabled the theme and even unloaded DesktopX, the taskbar started showing but explorer windows (in maximised state) occupy the whole screen, covering the taskbar. Does anyone know how to get my taskbar back to normal? There must be some registry entry or something.
Please help me!
Thank you!