Hello, I recently switched to a Logitech USB mouse from a MS PS/2 and upon doing so I was not able to go into the S3 stand-by mode anymore. This problem occurs when you want to wake your PC from stand-by with a USB device like a Mouse or Keyboard.
S3 Stand-By Explained - Suspend to RAM (context saved to RAM) In this state, your PC in standby and all fans, hard drivers and other devices are powered down into a sleep state. Power consumption is less than Five Watts.
After being in contact with Logitech customer support for over a month with no working solution from them, I went out to find my own. This is a solution I discovered.
Using regedit go to: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\usb
and create this entry: USBBIOSx = DWORD value = 00000000
**if you do not have a directory named USB you can create one for this fix.**
This is my source: http://support.microsoft.com/kb/841858