Reverted to Windows 8.1.
Problem solved. Not occurred in 5 days. Microsoft have failed to fix this simple and basic operational problem. Looking at Linux next as OS base. Microsoft have become complacent. Will not recommend to friends and family.
Please get back to us about how you get on. I can't believe this problem isn't being looked at and sorted as it is such a basic, but important, feature.
I'm having exactly the same problem. Never had it before. Used to close lid - laptop in sleep mode - open lid - unlock and resume work. Simple.
NOT SO SINCE WINDOWS 10. I have to force power off as laptop completely unresponsive. Unacceptable.