Just a heads up:
https://forums.inxile-entertainment.com/viewtopic.php?f=34&t=9214

Just happened to me, and installing in the same directory gives me an error.
Thanks for heads up, freaked me out a bit :)
Avast is THE FUCKING WORST.

Just open the virus chest and restore it. It will automatically go into exclusion list and won't bother you anymore. It happened to me as well.

Did that, following InXile Forum's advice. Still, that's pretty crap behaviour of my trusty antivirus :)

Very crappy behaviour. If a virus scanner is unsure if a file is infected or not, it should ask the user, not delete the file without notice. -_-
When I checked the virus chest, I saw a number of exe files which had been on my harddrive for like forever and which are 100% clean. Searching the internet I see a lot of people with the same problems.
I hope they'll clean up their act a.s.a.p.

That's Avast for you. Silent but on occasion overzealous. I have it on my home PC because it isn't much of a hassle. Just set it up and it will work in the background like it isn't even there. Of course, stuff like this happens sometimes. I'm sure that it will be solved in the next definition update.