I'm using Norton Internet Security and can't see anything untoward that would cause me problems...
I've had several sites where Norton was blocking content that was needed, and eventually found that some of the needed content was being blocked by the "block popup" option in Norton, which is only "supposed" to stop annoying adverts. For some reason, it also stops things that are wanted on certain sites. I guess it's down to the way the programmer coded the thing.
I've not tried Eurocontrol, and I've thrown out Norton for that and other reasons, so I can't help with specifics.