Like in the name of topic. The mouse is not working at all. Well at least I cannot move. The buttons themselves seem to have no problem with response, however movement is impossible. I also search the internet and I have found out that it is a known problem with this version. I changed the polling rate to 125 but it did not help. My mouse is Logitech G400s so it is not some no name...

One could think gog will make sure it actually works at it should be, at least as of mouse working, since I personally consider it a basic functionality...

Well it does work for a vast majority. Your problem is probably very rare and difficult to predict and could require the help of GOG support to fix. You're unlucky to be locked out like this.

O.K. I just tried again and now it works. I don't know if it is because of update that just downloaded or because I set it to Allow All in HIPS. So yeah it's OK, at least for now.

Anybody knows how to compare the mouse sensitivity setting to those of quake engine or source engine (which are the same...). Mouse-sensitivity web site does not have Aliens vs Predator....
Also it would be helpful to know how to set same stetting for vertical as horizontal since it seem a lot slower.

There are separate settings for vertical and horizontal mouse sensitivity in the Controls menu. Take a look around i cant remember exactly where it is, but it's definetly there. The same thing was bugging me with mouse being horribly slow when going vertical.

I found that ZoneAlarm seemed to be interfering for some reason. May not apply to your problem but could apply to others'. I read of several people having problems with mice on the steam version.