That's windows XP, allright? I've had this thing on all XP machines as far as I can remember, and this my new babie, one month old straight from the line, has made sure this nasty habit is not foreign to it either. It's probably got to do something with indexing of the HDD, as boguing pointed out, and laptops are no exception to this, unfortunately. Methinks all XPs in the world do this by default, and it only depends on how quiet HDD and sound insulated case that you do or not know about it.
Funny thing was, a mate of mine, a hard core unixman, would always rant about me being an XP sissy and why don't i migrate, saying Linux would never do what I haven't asked for. Now I have Gentoo at work and not only the thing digs on the hard drive like mad every now and then, but it beats windows to it hands down
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