Can't wake from sleep.

I have a windows 7 computer with Logitech K520 wireless keyboard
and mouse. Has the unifying USB receiver.
I'd been using it for a year without incident.
The keyboard or mouse would wake the computer from sleep.

Over the last two months, I've been trying to work the wrinkles
out of windows 10. I've changed a lot of windows settings, so
I restored a win7 backup from two months ago, before I started messing with
it. No help; still can't wake from sleep.

Pushing the power button on the chassis does to wake it.

But, if I plug in a wired USB mouse, that mouse wakes from sleep just fine.
I think that proves that the BIOS settings are appropriate. It's set
for S3 sleep.
I plugged a LED into the USB port to verify that it's still powered
on in sleep.

I've gone through every entry in device manager and checked the
box to allow this device to wake from sleep on all the entries
that had the option. Turns out that most of the usb/keyboard/mouse
entries don't have that option. Still no wake from sleep.
I've gone through the power profile settings and checked everything
that looks like it might have anything to do with mouse/keyboard.
I've changed the power profile from balanced to high performance...no
help.

I installed setpoint driver software. Now, I have two new device manager
entries
for the Logitech HID-complient unifying mouse and keyboard.
Neither has the option to wake from sleep.
Still can't wake from sleep.

I also have a Cirque GP410-U USB touchpad. It won't wake either.
Although the device manager entries are hard to decipher, given
that there a lot of mouse/keyboard/usb entries, I was able to verify
that the Cirque drivers are installed and working and
that the box to allow waking from the device is checked in both the
mouse entry and the HID entry.

I pulled the USB unifying dongle and plugged it into another win7
computer. The same keyboard and mouse can wake that computer just fine.

I think I've proved that the computer works and the keyboard works,
just not together...although they used to work fine. Previously,
I had issues with unwanted wakes from jiggling the mouse.

I set device manager to show hidden devices and uninstalled every
entry in mouse, keyboard and HID categories. I uninstalled any mouse
related software. Still no wake with default MS drivers. Reinstalled
vendor drivers. Still no wake.

I have no idea what to try next.
Ideas?