Hard drive stops/starts every minute

All,

The second hard drive working on the second controller stops and starts
approximately every minute. It's very annoying especially keeping in mind
that the second device on the same controller is RW-DVD and these ON/OFF
affects the writing on this drive. How can I make this hard drive always
working if BIOS switched to ALWAYS ON, Savers on laptop are also don't allow
to disable the hard drive or computer. What's going on there? Can this hard
drive disable itself regardless the Windows XP Professional settings?

The latest service packs are installed.

Dmitri.