On a Windows Vista-based computer that has the “Auto-hide the taskbar” option enabled, most of the taskbar does not appear when you move the mouse pointer into the taskbar area
Consider the following scenario:
- You enable the Windows Aero color scheme on a computer that runs Windows Vista.
- You enable the Auto-hide the taskbar option.
- You configure system display to use multiple monitors, and then you later you switch the system display back to a single monitor.
- You move the mouse pointer into the taskbar area.
In this scenario, only the Start button appears. The rest of the taskbar is invisible.
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB958908.