Well firefox has its own anti-phishing/security functions, see Tools, Options, Security, there are a range of options and also messages to be displayed or not, see image. Should firefox block a site in accordance of your settings it would normally alert you with a 'this site is blocked' or words to that effect, rather than 'page not found.'
The same with NoScript you can forbid sites, etc. but that is usually associated with underlying scripts not the actual web pages and you would have to have set those, so I don't believe NoScript is involved.