Windows folder with millions of files not responding

Well for a start, it looks like you have multiple Anti virus products which is never recommended and can cause the exact error you are saying - and usually a lot more serious as well.

There are a lot more things I can recommend such as checking all your shell extensions - (I wrote this answer in a previous answer)

I would recommend you take a look at [Microsoft / Sysinternals Autoruns][1] and look under the explorer tab. However, do not press delete on anything, use this to identify problems (by unchecking boxes) and when you have found the problem - use the uninstaller for the application. Only press delete if the uninstaller fails to remove it.

However, I really think that the error you are having is related to multiple AV engines.

My brand new PC running Windows 8.1 had a problem with Explorer.exe not responding, and it persisted after I upgraded to Windows 10. In my case, explorer.exe didn't stop running, but the task bar was no longer updated (clock was behind, notification icons out of date), I couldn't use alt-Tab to move between windows and holding the mouse cursor over icons in the status bar didn't display the associated window. Finding 'Windows Explorer' in Task Manager, right clicking and selecting 'Restart' would resolve the problem, but only for a little while.

I created a System Restore Point then used regedit to delete the explorer.exe subkey from HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution.options and haven't had the problem since then.

I posted this mainly to clarify that the explorer.exe "folder" referenced above is in fact a subkey. I puzzled over the nomenclature for a moment before realizing what TermoZour meant, and thought I'd post this to help others who might misunderstand.