I am running Windows XP and I tried to enable the iTunes toolbar on my
taskbar.  I wanted to see if it was anything like the taskbar player that
Windows Media Player has.  After I selected the toolbar, all of my taskbar
icons (running programs) disappeared!

I still have my Quick Launch icons and my language bar, but now the only way
to switch between active programs is with Alt + Tab.  I have tried rebooting,
and nothing has changed.  What can I do to fix this problem and get
everything working again?