I recently added a second hard drive to my computer and I am using it do dual-boot Linux (Ubuntu 12.04) with Windows 7. Both hard drives are SATA. I am using the default grub bootloader on my second hard drive. The windows drive is unmodified. To get to grub, I changed the hard disk boot priority in my BIOS (P35-DS3L) to boot from the second drive.
The problem I'm having is that when I boot to Windows 7 (on sda) from grub (on sdb), Windows 7 will not go to sleep (from the start menu). The display shuts off momentarily as if its going to sleep, then comes back on and displays the switch-user screen. Powercfg -lastwake does not show anything.
I am sure that this is related to booting from grub on sdb because when I change the hard disk boot priority in the BIOS to boot from my (unmodified) Windows hard disk, the computer goes to sleep fine.
It occurred to me that installing grub on sda might solve the problem, but I'd rather not since I like to have my windows hard disk unmodified so that booting to it from the BIOS boots directly to windows.
A possible work around is to use the BIOS as a bootloader, by pressing F8 to select the boot device. Still, I'd like to know why the problem is happening in the first place.