Hello, here is my situation:
I bought a Western Digital 120 GB SE drive for my iMac DV. It will sleep fine running 9.2.2, but when I try and put it to sleep under 10.2.4, the rest of the machine sleeps while the new hard drives sounds like it's spinning up and spinning down, again and again.
Since it works in 9 and not X, I'm thinking it's not really a hardware issue and a problem with OS X instead. Not sure if Peripherals is the correct spot to post or not.
My iMac:
iMac DV 400 MHz
1 GB
120 GB WD 7200 rpm SE
9.2.2.
10.2.4
Brad