Eddy
2
1]
Make sure any pre(vious) installed av is completely removed. (including avast)
Links to tools/tutorials > http://www.ache.nl
2]
Cleanup your system, bot registry as well as (temp)files.
3]
Download the complete installer.
https://forum.avast.com/index.php?topic=189836.0
4]
Try to install avast.