Norton Antivirus is known to block referrer header, try, as a test, to disable it momentarily while you download, if that works then enable it again and check your settings etc. If you can't find anything then ask Norton for support, I don't think anyone here uses Norton.
Im using Norton and PC tools spyware and virus protection all at the same time and have no problem with it what so ever. never had to change any settings on it.
I can see how script blocking might relate yeah, though I wouldn't know, nor do I have any intentions of installing it to find out.
