Have been using XP Pro op system on a desktop for several years and updating as usual, but recently having this unusual problem of loosing the screen 'Toolbar', which of course have the 'Start' button and all other screen icons. As I loose the Toolbar, I can still use the mouse and 'refresh' the screen, but the Toolbar does not reappear anymore. Any idea what causes this and how to fix it? Usually this happens only when the PC is left 'on' for some time without touching the mouse. To re-boot the PC, I have to turn off the power switch. 'Control-Alt-Delete' or the Task Manager does not work anymore. Appreciate any suggestions.