Norton Internet Security

[cd34]

I looked at Barron's page and noticed that the top graphics were 120x90, a standard iab unit. The ones that did display were not iab sized.

IAB set standards a while back for adunits so that publishers and advertisers would know exactly what was being referred to.
http://iab.net/standards/adunits.asp

I wonder if Symantec believes that images that meet IAB size guidelines are advertising -- regardless of the site.

And yes Natalie, urls with the word 'ads' appears to be a trigger.