I ran into a situation (confirmed by a Norton tech via Chat) whereby, if Norton AntiPhishing is turned on, a web page (otherwise deemed OK by Norton Safe Web) may be prevented from fully loading (but without any message to this effect) if it contains links to web pages or services NOT deemed OK, e.g.., adclick. As a result, the user is left looking at a partially blank page but has no clue as to why this may be.
Both the tech & I agree that if this situation arises, it would be far preferable to have Norton display a message to the user stating something along the lines of "To protect your computer from possible harm, portions of the web page you were viewing (which included links to potentially unsafe websites) were not displayed. Please inform the Webmaster monitoring the site of this problem."