Erratic mouse/cursor behavior

I have a Dell Inspiron 4000 laptop and over the past year have had problems with my mouse/cursor. Periodically, when I log on, my cursor will slam against the edge of the display and I have to fight to bring it back. I talked to Dell technical support and they told me to re-format my hard drive.(This seems to be the big hammer approach) Not wanting to do this, I just tolerate it. Sometimes I log in and its fine other times I just have to keep rebooting until it behaves. I have run virus sweeps and updated my drivers but the problem still exists. My next thought ist to update the bios. Does anyone have any other ideas??