Right-click the Start button and choose Properties.
In the Taskbar and Start Menu Properties dialog box that opens, click on the Taskbar tab
Put a check at “Keep the taskbar on top of other windows”
If that does not help try this
http://www.kellys-korner-xp.com/xp_tweaks.htm
Line 99 left hand side
Save the REG File to your hard disk. Double click it and answer yes to the import prompt
.