It seems that you are not alone:
http://www.cablehell.co.uk/forums/index.php?sh owtopic=25314
If you do plan to take the advice in the link above, it seems that NetGuard lives here: C:\Program Files\ntl\ntl Netguard.
Your problems may be compounded if you have a firewall installed (e.g. ZoneAlarm) - this is something that is mentioned in the FAQ over here:
http://www.virginmedia.com/helpsupport/netguar d/faq.php
Sorry I can't give an exact answer, I don't use NetGuard personally!
HTH