Power management and keeping HDD turned off

[sojourner]

Was inspired to do some work with power management on a T41 recently. Was able to get power consumption down to a meager 7.74 watts with display on low. With a 9-cell battery the Battery Info display showed a whopping 9.5 hours run time! Not bad for a T41

There is however a hitch here, I cannot get the HDD to stay off. Something must be accessing the disk because it will turn off then sometimes immediately turn back on! Sometimes it will turn off for 5-10 minutes then turn back on. I've looked in the event log for clues as to what's causing this and found nothing. I've opened task manager and followed CPU use, and although there is always some cpu activity (eg, explorer, nhc) there is still no clue as to what keeps activating the HDD. There are no virus's, no malware ... what can be activating the HDD?? Log files being written to?

EDIT: Bluetooth is also install (XP OS BTW), could Widcomm's BT stack be doing this?

[aaa]

Sysinternals has a couple of disk monitoring tools.