His name is Konstantin. When he downloads some videos from the Internet he sometimes catches viruses. His antivirus software doesn’t work properly . He sees the black screen, the system shuts down, he waits for some minutes and switches it on again. After that all the emails that Konstantin sends usually have  а virus in the attachment . I always say to him “Change your software or stop downloading these videos!” He says “It’s none of your business ”. I have nothing to answer, he is my boss..