I’ve had the same issue and I’m not very pleased with my computer being hijacked like that. I did not ask for this piece of software to automatically start up when windows booted and I cannot switch it off using either of the buttons provided. Task manager is inaccessible as well.
I suggest Avast sort this out. I need my PC for my work and now I cannot get in to the thing without booting in to safe mode.
I’m using windows 7 ultimate and just updated Avast to have this crap forced on to my PC. Again I did not click an option to allow this, I rebooted and bang, a stupid overlay that cannot be closed.
Uninstalled Avast now, stay well clear of it.