I became infected with Sysguard.exe (root for Spyware Guard malware). I bought and installed Zone alarm and it found 220 infected files but did NOT get rid of Sysguard.exe. I keep stopping the process and deleting the file but it returns immediately and Zone Alarm doesn't recognize it as a virus/malware. What do I do?

Operating System:Windows XP Pro
Software Version:8.0
Product Name:ZoneAlarm Internet Security Suite