All M571 Motherboards suffer from what has become known as the "Hard Drive Spindown Problem". This phenomenon only seems to occur when there are drive(s) connected to the secondary IDE controller on the board, the result being that some or all of your hard drives will spin down after about 15-30 seconds of inactivity. This problem is not related in any way to any APM settings in bios or whatever OS you may be running. It is a bug in the bios code.
The best way to fix this problem is to update your bios using a bios flashing utility and the latest bios update.
If do not feel comfortable messing with your bios, you can download a "hard drive sleeping utility" to keep your drives awake. One such utility is HDSleep. It runs in the system tray under Windows 95/98/NT4 and is shareware. I am not aware however, of any utility that runs in DOS or any other OS.
Download "HDSleep" - Zipped (68k)