Ive been running windows 10 64 bit on Toshiba Satellite P845T for a few weeks and have recently encountered the problem above…. if I leave the computer idle for a minute it goes into sleep but then flickers between unlock screen and black screen, I have to keep logging in to carry on. all my power settings are set with never to try and resolve but the laptop appears to be taking no notice of the power settings. This is a major problem for me as I use the laptop for presenting.

I did find this solution on another forum:

Here is the solution that worked out for me:

1. Click on the windows icon
2. Type regedit
3. Right-click on regedit icon, click Run as administrator
4. Go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\PowerSettings\238C9FA8-0AAD-41ED-83F4-97BE242C8F20\7bc4a2f9-d8fc-4469-b07b-33eb785aaca0
5. Double click on Attributes
6. Enter number 2.
7. Go to Advanced power settings (click on Windows button, write power options, click on Power Options, in the selected plan click on the Change plan settings, click on the Change advanced power settings).
8. Click on the Change settings that are currently unavailable
9. Click Sleep, then System unattended sleep timeout, then change these settings from 2 Minutes to 20 for example.