Why does the behavior of the quick launch bar and the Windows start button change after a few hours?

Question

Windows

Good day.
There is Windows 8.1. When you start the computer, everything works like a clock, but after a certain number of hours, annoying symptoms are observed, which, in principle, are not bugs in themselves.
The first is the inability to click on the "start" button without moving the cursor there. I point at the button - and the adjacent icon is highlighted, zero reaction to the actual click. After the restart, this feature, lovingly inserted by the developers, disappears, and everything works as expected (the Windows button reacts to hover with a color change and overflow). Screenshot of the bug:

Second - keeping focus on the icons of the quick launch barafter she turned around. I moved the mouse over the panel, then switched to the working window, and a tooltip with the name of the application that the cursor was above comes out from below. physically focus is saved ! Screenshot (I opened the panel, the cursor is physically in a neutral place, but the focus on IE was preserved):

The problem is relevant for the entire generation of windows after the beautiful Windows XP. It hasn't been fixed since Vista, I guess. It was also in the seven (but I attributed the seven to the crookedness), but now this bug bothers me in Win 8.1. I'm afraid if I upgrade to Win 10, it will also appear there.
Relevant for several computers, one of which is guaranteed to be clean and with licensed Windows, so the problem is not viruses. Perhaps the problem is in the applications, but nothing junk is installed and never installed (usual developer environment + Comodo).
As expected, nothing is written in the logs.
Any suggestion? Apart from installing Linux, of course.
Thanks in advance.

Answer 1

Problems with Explorer (i.e. with the shell). This happened to me on a laptop with a 5400RPM HDD, it was torn apart by I / O and the start was opened for about a minute :)