It's a pretty standard Win 7 box. Sleep is enabled, but Hibernate/Suspend are disabled, and always have been. I replaced the PSU and case two days ago. Save for that, everything else is a few years old. Up until I replaced the PSU, I never had this problem.
When the computer puts itself to sleep now (after 30 minutes), they keyboard no longer wakes up the computer, nor does the mouse. Both are marked for "Allow this device to wake up the computer" and have worked perfectly until the PSU swap.
Pushing the POWER button on the case starts up the PSU, but the computer does not respond. Though I can hear the system fans spinning, neither the keyboard nor mouse LEDs get power, and I can't do anything to wake the PC.
From this mode, the only thing I can do is hold down the POWER button for five seconds to force a full power-down, then push it again to power it back up. BIOS passes fine, but Windows chokes and says it failed to shutdown properly, and should we startup in Safe mode, or Normally.
Since all the software settings (sleep, power on devices, etc) have been untouched and were working before the PSU switch, I'm not real sure where to look for the problem. I suspect BIOS ( looks like this one
), but I'm not real sure what it would be.