Mouse and keyboard are wireless with receiver.  (Tried in all the available ports).  Option in DM to allow computer to turn off is not available (greyed out)

Just curious, The Dell mouse is Bluetooth, were the others you tried Bluetooth or were they simply wireless with a receiver? And is the Power Management on the Dell mouse set to allow computer to turn off?

What about USB Devices and Human Interface Devices listed in Device Manager? If any of them is set to allow PC to turn off the device on their Power Management tab (if they have this tab) in Device Manager, uncheck that box.

Next, look on the Advanced Power Options screen for your active Windows Power plan and disable USB Selective Suspend too.

Reboot when done...

Individual HID PC to turn off is not available to change, greyed out.

Advanced Power Options does not have USB Selective Suspend Option in either Windows or Dell advanced plan options.

Again, the only mouse that is an issue are either of the two Dell KM656 that I have.  The original and the replacement that Dell sent.  Now tried 5 others of various brands and can not duplicate Dells issue.  PC user since the Commodore 64.  Never been this stumped. Can't think it's anything other that the mouse's internal standby/sleep/battery saver firmware that is at fault.  There's no way to change that.  Also weird the lack of being able to find similar issues in searches except when a dirty mouse is involved.  These are brand new.  

This is an ongoing issue which doesn't only affect mice; the keyboard shipped with the 7700 All-in-One machines misbehaves as well - failing to record keystrokes and randomly repeating letters, sometimes 20 or 30 times, even with careful adjustment of the repeat delay and repeat rate settings.

It does not seem to be a settings issue. My gut feeling is useless drivers that need to be rewritten.

My solution has been to set the supplied keyboard and mouse aside and substitute a Logitech set which functions perfectly.

Ed Form

Agree.  Terrible to ship such a cheap keyboard/mouse with an otherwise great PC.  Dell won't admit there is in fact either a driver or keyboard/mouse hardware issue.  I'm using a Logitech without issue.  Just want to get what I paid for...........a working mouse.

I pinged my Dell tech contacts...

This issue is still open and probably there is no easy solution.

I came here in Nov-2019 to comment about this issue in this thread and is sad to know that more threads are being opened to report the same problem without a solution.

Yes, I recently purchased the same computer and am having the exact same issues plus some other quirks.