I assume you are talking about clicking on the images in the search results of a Google Image Search (as clicking any old image should not do anything unless it is a hyperlink).
In this scenario Classilla doesn't work for me either. It seems that Google detects the Nokia user agent and diverts you from the proper URL to an
http://images.google address. (Why?)
The resulting Google page does not work with Classilla.
The workaround is to change the user agent. With the Classilla user agent selected, clicking on the image search results takes you to the correct URL containing that image.
Another alternative is to use iCab, or IE, or Netscape.
I can't explain why the installation of iCab had any impact. It seems coincidence to me.
Google Images seem to have made some changes (about a year ago?) In the past, when you clicked on a Google image search result, it took you to an information type page, and from then you could go to the actual image ONLY. Now you have to load the whole page that image is on. It's really annoying....