I installed Windows 10 on my Acer laptop today. Everything went without a problem. After the installation, the start menu could not be opened and Windows advised me to log off. That didn't work and a restart didn't change anything. Even "sfc" and then "DISM" did not help. Then I created a new user. When I signed up there was only a black screen. I tried to start the task manager with Ctrl + Alt + Del, which also didn't work. After a minute the message came up again: Serious error, start menu does not work, please log in again.
I'm now at a loss and hope that you know an answer.
Please download an alternative start menu like
https://www.startisback.com/
It looks like a Windows 7 start menu, but it works very well
Take the free trial version