win10 randomly crashed while idle. Some kernel security bsod.

after reboot, the start menu does not open in the lower left corner. It opens in upper left corner, and none of the menu is clickable. I have to use keyboard arrow keys to navigate.

Also, when I start typing words to search for apps, the search menu opens full screen.

My start menu is corrupted. How do I restore it? Event viewer suggested my .dat file is corrupted.

Even creating brand new user, the start menu still opens in the upper left corner (while the start button is in the lower left corner), and the menu is not clickable for the new user.