do you have it on auto-hide? are you using any windows style programs? doe it come up when pressing the "window" key?
did u lock the taskbar??? because if you didnt, you could have accidentally dragged the whole bottom bit.......just move it back up if its hidden...that could be the problem
its ok i think i sorted it.i had a screensaver,the warriors game one and it just comes up every 10 mins evenin if im on the computer but i changed it now so its ok