Hi Stephen,
Are you using a Das Keyboard?
Sleep/wake 'breaks' Das Keyboard
https://forums.macrumors.com/threads/sleep-wake-breaks-das-keyboard.2045736/

Sent from Ronni's iPhone 7 Plus

> On 24 Sep 2017, at 12:52 pm, Stephen Chape <chap...@bigpond.com> wrote:
> 
> Hi folks.
> 
> I have had my new iMac for about a month.
> iMac 21.5 inch i7 with 16GB RAM 500GB SSD
> 
> Three times since setting up it has lost Keyboard and Time Machine input.
> Each time I have returned after leaving it unattended for a while.
> 
> When I try to log back in using my password there is no keyboard input.
> And the Time Machine HD has unmounted.
> 
> If I restart the iMac everything is back to normal.
> 
> Any ideas please ?
> 
> Regards,
> Stephen Chape
> 
> 
> 
> 
> 
> 
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