When trying to install the game Nox using the GoG installer Avast shows this
http://i.imgur.com/O0FglUw.png
and breaks the install. I believe this to be a false alarm and in that case how do I prevent Avast from removing it?
Hallå grabben 
have you tested the file at www.virustotal.com
post link to scan result here
report and upload the file to avast lab here http://www.avast.com/en-no/contact-form.php
if you have the file in avast chest , you can also right click the file and upload from chest
I am not sure on how to get the file since it is a temporary file and Avast seems to just remove it.
Avast detected Trojan when trying to launch the game after installing it with real time protection off. This is the virustotal.com scan of the file detected by Avast: https://www.virustotal.com/sv/file/b77315104d95ce9ae34e809fd2570d956d0e2bda3bdbd7973e0dfc326020b886/analysis/1367664721/