I have a less than 3-year-old Dell Studio laptop running Windows 7, Internet Explorer 9. I use the touch pad, not a mouse. Lately the scroll bar moves on its own and the cursor does, too. The cursor bounces all over the place. This is driving me crazy! "I've read some of the answers to this question but I either don't understand what they're talking about or my computer doesn't have the "category" they say to click on.
I've found before that wireless interference from another wireless input device can be a cause of similar problems. Maybe you could look for other wireless input devices in range?