Are you having a hard time trying to remove a file called koos.exe? The symptoms are: your firewall tells you koos.exe is trying to call out. Along with antivirus programs telling you koos.exe is a virus.
Koos.exe is a Trojan and it acts like a rootkit. You’re going to want to use AVG’s Anti-Rootkit software to remove it. I used it tonight and it worked well.