Task Manager Menu Bar and Tabs Are Not Visible in Windows XP http://support.microsoft.com/default.aspx?scid=kb;EN-US;q314227
This behavior may occur if Task Manager is running in Tiny Footprint mode. If
you double-click the empty space in the border around the tabs, Task Manager
switches to this mode.
To switch Task Manager to its typical display mode, double-click the top border
of the window.