Originally posted by andrey
1) turn off all network adapters
2) close all network ports except really needed for you in firewall
3) change administrative password for all users in Administrative group
4) remove
4.1) on 64bit machine HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\PLESK\PSA Config\Config\papswd
4.1) on 32bit machine HKEY_LOCAL_MACHINE\SOFTWARE\PLESK\PSA Config\Config\papswd
5) remove all unrequired users from Remote Desctop Users group
6) remove all accounts from Administrative Tools\Local Security Policy\User Rights Assignment\Allow log on through Terminal Services, then add only self account to this privilege
7) run netstat -a -o and ore
7.1) put here output
7.2) close and move to some temporary folder all non Microsoft and non Plesk program from netstat output
8) restart Plesk services
9) remove all urequired applications and drivers
9) turn on all required network adapters
10) resrart your machine