This is almost certainly a false positive. I am getting the same with files downloaded from my site (http://www.jeffg.co.uk). My programs are built using Microsoft Visual C++ in Visual Studio 2010. Someone else has the problem with programs built with Dev-C++. I have submitted a ticket but Avast seems to be doing nothing about this. Would be worth contacting the people at www.jzk.pl to find out what their programs are built with.
Edit: which programs from jzk.pl/pobierz show the problem? Because the first one I tried (Druczek Ultimate) was OK. I tried several others too, without a problem.
In my case this is certainly a false positive and is giving me a huge headache.
I have a program written in C + + and I compile it using MinGW. AVAST thinks this program is contaminated with WIN:Eco-gen, and I’m pretty sure is not because it is my own program. It is part of my installation package and is causing problems in all my customers.
What I want to know is what I have to do in my source code for the AVAST do not identify it as a virus?