How to destroy a virus on the network?

Question

Malware

At the enterprise in a network almost simultaneously at all computers began to work badly. It takes a long time to load, then reboot on its own, then the network flies, then all sorts of windows pop up every 5 minutes. In short, I found that everyone had services with random 4-letter names, such as mSkl, xDfa. All have automatic start. The command to run is either cmd what is there tra-la-la, net what is there tra-la-la, c:\installed.exe. Also the Driver service, with an incomprehensible description. All this swamp of Kaspersky Virus Remve Tools 2015 is being treated. But while you cure one computer, the same one pops up on the other. Almost all machines are on XP and 7. Modern antivirus cannot be installed there, it asks to install all sorts of updates that are also not installed (certificate not found). How to be, who knows?

Answer 1

Disconnecting all machines from the network.
Cleaning infected LiveDisk machines with fresh antivirus installed.
Turning the cured machine back on the network