There might be dirty links (pun intented), but I strongly doubt pictures hosted on the board contain viruses. Are there any other users who might be able to identify the offending page (through their antimalware or antivirus software popping up)?
pictures on biocosighting like isightcast
Hmm that's strange if you're getting the popups from the attachments themselves. I know in the old board we had some issues with dead links giving popups but that seems to have gone away.
I always run basic ad-block and it seems that Chrome is blocking any "scripts trying to run from unauthenticated sources"