Hello BruceLee,
Can you try booting into safe mode? When you boot your computer up keep hitting F8 every second or two until you get to the boot options screen. Choose safe mode.
Once you are in safe mode, test your trackpad then. If it is still having the same problem, test a USB mouse and see if it does it with that. If it also does it with the USB mouse, that would indicate a possible problem on the motherboard.
If it doesn't have any problems in safe mode, then I would suspect a software issue. If you do think it is a software issue, try following my Pre-Work link and posting the results in the HijackThis! Logs forum. One of our security staff will check for malicious software.
Hope that helps!
