Hello
I'm having the same issue, on Lenovo Yoga 500-15, with the same strange behaviour: when Task Manager (or some other panels such as Device Manager...) is displayed, everything is fine!
I ran the commands you suggested but it did not solve the issue.
My Yoga was upgraded to Windows 10 by installing it from a USB key, and then installing all the drivers for Windows 10 provided by Lenovo and updating Windows.
Any suggestion on how to go further? I could not see on Lenovo site if Yoga 500-15 is supposed to be compatible with Windows 10. Almost all drivers for Windows 10 are available from Lenovo support (with a couple of exceptions), but no Lenovo utilities (OneKey Optimizer etc.) is provided for Windows 10. Maybe I should wait that Lenovo clarifies all that...