Dell :: Hard Drive Clicks From Time To Time

My laptop is an inspiron 1520, about a year old now. Ever since I've had it, the hard disk drive has been making a loud, random click from time to time. Sometimes, it will click twice in the space of two minutes, sometimes it will click only once in two or three days.

Typically it's simply a loud snapping sound, like if you get a pencil and snap it against a wooden desk. It doesn't make any other sounds besides the usual hard drive sounds.

For about a quarter of a second, the system pauses. I think it's related to heat, as it happens most often while playing a graphic-intensive game.