If you're lucky, it may not be a hardware problem at all. A common cause for this is a little dust or dirt build up in the lens area underneath the mouse or even on the touchpad itself. Make sure this is all clean first (use a dry cloth for the touchpad). Cheap mouse pads can cause these symptoms too (poor design which doesn't reflect properly.)
If the problem continues, and the computer is still under warranty, the definately go through the correct channels to get it to an authorized service agent. Opening it yourself or taking it to the local PC shop will void the warranty every time - and all computer manufacturers are very harsh on this - for the simple reason that most shops don't employ anyone with formal IT qualifications.
