Avast Free stuck at installing

So I’m installing a laptop (Lenovo Y70) from scratch with Win 8.1 Pro. Was going to install Avast Free but it’s stuck in some strange “silent install”. The install process is running in the background but nothing happens. When I try to fix it I get “Setup is already running”. After a while, the computer freezes completely and I have to do a hard reset. After rebooting, it’s the same thing again. The install process is running and I can’t stop it. The account I’m using has full admin rights.

I’ve search for this error but can’t seem to make it work. There is no Avast icon at the clock, so I can’t open any user interface and the two active Avast-processes can’t be terminated through the Task manager. Also, the avast uninstall tool does nothing. It’s progress bar just goes back and forth for ever.

Any tips?

What other AV is on your computer or, was on your computer before attempting to install Avast?
How was the other AV removed? What other security related programs are you using?