I can't see the buttons on the left and on top

I've installed ubuntu 10.10 for netbook on a HP Pavilion dv4000 and i can't see the buttons on the left side and on top. If i go over them i can see a white box with no text. When I click programs appear and i can see all off it. But still i can't see the buttons on the left nor those on top. Only when i open two windows and go with the mouse pointer from one to the other the buttons appear for less then a second.