I too have the exact same issue and it has to do with the target tag. From my own research, Zone Labs is automatically assuming that an image linked to a page not from the same URL is an ad! Zone Labs need to fix their code. I link to other artist websites so its all personal names and such and their banner images range from really small images to large ones. It has to do with the target tag.
This is a REAL issue and Zon Labs should update their ad block codings to something a little more stable. I shouldn't have to code all my sites differently just to make sure those using a Zone Labs ad blocker (like I do) can see my site's images! Especially when I am using web compliant code! I've run across other sites that should have images, but nothing shows up as well. I use Firefox, Opera and IE- all more current versions. Same issue in ALL browsers. THis is a ZONE LABS issue and one they should fix.
In reading the original poster's response they got from Zone Labs, I'm not gonna even bother with my own issue but I will look at other security systems rather than renewing with Zone Labs when my current subscription expires.
VERY DISAPPOINTED in ZONE LABS. Using PRO Suite, latest version.