Thinkpad 600 Power Management Issues (HD turned on and off)

Hello,
 
I have recently installed 4.5-stable on a Thinkpad 600X (BIOS version
ITET53WW), and the hard drive sounds like it is being turned on and off
every few seconds.  This was happening after the default install, and it
is still happening after the custom kernel build.  (I haven't done
anything specific for power management in the custom kernel other than
leaving the "device apm0 at nexus?" option, which was there in the
GENERIC anyway.)  The kernel file is attached for anyone interested.
 
Does anyone have any tips on this?
 
Regards,
Kenan