just found where system updates are (in a way) affecting images.
click to enlarge isnt working on active auctiva listings.
here's url from an auctiva listing with click to enlarge (the url that loads when you click) -
http://www.auctiva.com/hostedimages/showimage.aspx?gid=...2&formats=0&format=0
as you can see, gives you a message about system being updated.