There is a closed thread titled "Start Menu keeps opening". I don't know why The_Prophecy closed it as solved when it's clearly not solved. For the case where this happens on ASUS ROG (gaming laptops) the solution appears to be to uninstall the ASUS Screen Saver. See this link; https://answers.microsoft.com/en-us/windows/forum/windows_10-start/start-menu-pops-up-randomly-win8-win10/873059b9-cb09-4bf5-b970-a0b5b091576b