A little ditty for you for future reference:

Several times over the last 2-3 years, I've had some strange hard drive accessing goin' on and couldn't pin it down..some of you recall me bitchin' about it...and there's been thoughts that it was a worm or trojan, as they will display that symptom...constant grinding in short intervals with NOTHING happening, no other activity at all...

Well, it happened appr. 4 months ago...I did a complete conflict test with Conflict Catcher...it took FOREVER, but it tracked down a BUNCH of native system things like Open Transport files...FUNNY THING, with the Mac OS base set on it didn't have the problem...and CC didn't flag ANY 3rd party extensions as being a problem. I did a complete format to solve it then, cuz too many files were being flagged as the culprits.

Anyway, I did a clean install...same stuff after I did it, constant churning at the drive. This time, I disabled all the Open Transport files, and the problem disappeared.

I trashed them, and tried to empty the trash...the following files were "in use" by the system (I wasn't engaged in ANY network activity) and couldn't be deleted:
Open Tpt AppleTalk Library
Open Tpt Internet Library
Open Transport Library
OpenTpt Modem
OpenTpt Remote Access
OpenTpt Serial Arbitrator

I started from another drive and re-installed Open Transport from a OS install CD, and the problem vanished.

Soooo...as I have heard others have the same trouble (I recall a couple of news posts about it), perhaps this will help if you get strange unexplained hard drive accessing.

Don't panic, you might not have a trojan or worm, it may just be buggy system files!

btw, this happened on OS 8.6...cheers.