Disconnect the computer from the internet immediately
Kill the SS32.exe process (or whatever process you suspect has been launched) via task manager
Scan the disk for SS32.exe and delete any traces of it.
Run a full antivirus scan
Download the VIPRE Rescue Scanner (google it) and run this on the PC.
Run any additional malware scanning/protection utilities you care to.
Go into Control Panel > User Accounts > User Account Control and turn UAC back on if it appears disabled
Restart computer and assess situation, consider plugging internet connection back in if you think the threat is gone.
Zen 8000 Pro