If Windows 10 Start Menu or Cortana search box keeps popping up randomly or opening automatically on its own, here are a few troubleshooting steps you may want to take a look at. This is a weird problem some people are reporting to be facing and there really do not seem to be any answers. Nevertheless, there are a few things you could check on and see if they help resolve your issue.
Start Menu keeps popping up or opens randomly
You may try these suggestions in any order you wish.
1] Physically check your WinKey on your keyboard and ensure that there are no particles lodged there and it is functioning properly.
2] Update your Synaptics/Touchpad device drivers and see. If you updated them recently, then rollback the driver and see.
3] Open your TouchPad settings. You will be able to access it via Control panel > Mouse properties & settings. Configure your Touchpad settings like Pressure, etc properly. Did that help? No? Then disable 2-finger & 3-finger scrolling and see. Does unchecking Right Edge Swipe help? If not, you can, set all settings to Default and see. If even this does not help, disable TouchPad and see.
I have displayed Dell Touchpad settings, but you will have to search for similar settings on your device.
4] If you have any third-party Start Menu replacement installed, uninstall it, run System File Checker and see if it helps.
5] Hide Search or Cortana icon in Taskbar and check. Right-click on the taskbar, select Cortana and choose Hidden.
6] If you have 3-finger tap to launch Cortana enabled, disable it and check if that helps you.
7] Use the Windows 10 Start Menu Troubleshooter and see if it helps.
8] Perform a Clean Boot and see if this problem persists. If it does not, then you will have to identify the offending software which is interfering, by trial and error method.
9] Click on the Taskbar Cortana button, open Cortana settings and toggle the Taskbar tidbits switch to the Off position.
10] Completely disable Cortana and see if that helps.
TIP: This post will explain why Windows 10 Start Menu is always opening up after Sleep or Hibernate.
Let us know if any of these suggestions helped you or if you have any other ideas.
See this post if Help windows keep opening automatically.