I just restored my system (clean install) from previous infection. Everything has been working fine for the first two days. Now I can't find nor start windows defender, firewall, security center. Running various anti-virus and anti-spyware apps did detect some trojans and my router does list some attempts at pinging my PC. I also found a file called PING.exe that keeps trying to run. I am unable to either modify it nor delete it. Any ideas?