mouse going haywire

hi there,

my laptop has been driving me nuts and i am hoping someone can help. the mouse has a tendency to drag off into the corner of the screen if i bump the laptop in any way. or if i try to click the button. i can only tap the touchpad to click on any selections or the mouse will go haywire and drag off to the corner. when this happens, all i can do is wait and hope that it stops soon. usually it takes a few minutes, but sometimes it goes on for hours. i can't get anything done and feel like i am constantly walking on eggshells as the slightest bump or accidental click will set the mouse off. does anyone know why this happens or how to fix it? it's a dell latitude c510.

thanks!