Task Manager does not work

Dears,

I've a Hp Envy 17-j009el with Windows 8.1. Recently my task manager doesn't work.

I've checked for virus with avast free edition, but not virus have been found.

I've also try the solutions suggested here withous success:

http://windows.microsoft.com/en-us/windows-vista/troubleshoot-task-manager-problems

Could be a conflict between avast and intel driver as suggested here?

https://feedback.avast.com/responses/black-screen-after-log-in-windows-8-task-manager-dont-start

Ive also installed Process Explorer as alternative Task manager, but it's doesn't work too.

Thanks

tizi27