I just got hit by an electrical shock when my left index finger touched the brushed aluminium panel encasing the touchpad of my laptop. The discharge was strong enough to give me a jolt me and temporarily numbed the tip of the finger. A search on Google revealed that this problem occurs in Dell XPS series, MacBook Pro and other makes of laptops with similar metal panels. I am currently using the Dell XPS M1330. Hopefully, this is just a static discharge instead of an electrical leakage of the system. My laptop is already connected to the power socket via a three-pin plug.