Seems to work fine on Firefox version 3.5.5 Bewertet mit 3 von 5 Sternen

This add-on seems to work fine on my machine, I have Mozilla Firefox version 3.5.5

I would like to note that the reason this page's threat level shows as Elevated is purely due to having the "McAfee Global Threat Condition" option selected in the 'Sites to use' section of the "Viral Threat Level Options".

My recommendations would be to check ONLY the following two boxes (for a better/real-time accuracy).
1-Symantec Security Response ThreatCon
2-ESET Virus Radar