What I was thinking was that perhaps your PC's might have some spyware on them that the RCU firewall is not letting get through to the site - not necessarily a virus, just spyware. It' may not be that the problem is with RCU, but with you trying to get on to RCU and RCU is giving you a heads-up, so to speak. But that's just a guess on my part.
IF you head up to
www.lavasoft.com you can download Ad-Aware. You can buy it or use the free download. I usually run mine about once a week and get about 30 'hits' that the Ad-Aware cleans out.
Just a thought,
Bob