during the install process avira pop up a message :
found a virus or malaware TR/ATRAPS.Gen'[trojan] in file 'D:\Program Files (x86)\GOG.com\Battle Isle Platinium\Incubation\launcher.exe'.

I got the same message from my antivirus program. I consider this to be false alarm but clarification from the GOG-people would be nice.

Seconded. I bought the pack mainly for Incubation. Now I'm a bit uneasy about playing it. What antivirus programs do you use. I've Avira Antivir installed.

Avira Antivirus Pro

Generic trojan warning? Sounds most likely like a false-positive by your anti-virus program. Try uploading the file to http://virusscan.jotti.org and see what other scanners say about it.

Thanks for the link. I uploaded the "launcher.exe" and Antivir is the only program to detect malware in this file. It's not the first time, that antivir produces false positives.

Avira Antivir is legendary for producing false positives. Microsoft Security Essentials is worth checking out.