For the first few months after I got my Dell Latitude D820, it worked perfectly fine. I noticed a small problem after a while. The mouse would randomly and suddenly whoosh to the lower left corner of my screen, and occasionally the upper right. This may have stemmed from an incident where I dropped a book on the lower left quadrant of my keyboard (so to the right of the trackpad). A slight impact there (like if you slap it) will cause the mouse to do this again. If it is moving slowly, my trackpad can still control it to a point, but if it's moving quickly, only my trackball can gain back some control.
After I got a mouse the problem seemed to stop being so weird, but has slowly returned. It rarely moves quickly, but my mouse can sometimes gain control back. Lately, however, it's been moving softly and slowly to the upper right or lower left. It's never clicked a thing and it's the only part not working properly, so I don't think it's a virus or a hacker. Please help me, as this is doing horrible things to FPS games and Minecraft.