The infections were in my previous computers. I was using Windows, flashdisks, etc. I was aware of nothing.
After this bad experience I read about the topic and bought a new laptop and a connection. I verified the Whonix images by gpg4win with different signature files downloaded from different Tor circuits. I downloded gpg4win using the certificate from https://ssl.intevation.de
May be I became paranoid but I had enough reasons. Before Whonix I wanted to install Qubes and decided to buy it from www.osdics.com by air-mail and I asked a question to Marek Marczykowski Gorecki about the trust level of that company. He said to me that the web page did not sell qubes and maybe someone wanted to send me a fake DVD. I checked it from a different computer and connection that yes! they were not selling Qubes! This is something like Postman-In-The-Middle-Attack.
If this download promlem is not a virus-infection indication, there is no problem for me. I can download Tor browser manually and verify it.