Nothing like this. Antivirus Kaspersky and Avast poorly upgraded. Very often they do not see viruses on the PC. And when another program is installed, it immediately finds and eliminates these viruses.
It's true. With the picture on the PC, the virus downloaded from the network somehow. Kaspersky was installed. He did not detect the virus, and the PC began to work poorly and to buggy. Has carried to the master, that new anti-virus program has installed and the virus has rendered harmless.