can't browse zip files in image viewer

I am suddenly unable to browse inside of zip files in image viewers. I was able to before, and then it just stopped working. Instead, it either dosen't open at all, or opens an archive window, rather than going into the files and letting me view the images.

I have tried two programs, Gwenview (did it, then stopped) and Showimg (should do it, downloaded after Gwenview stopped doing it), which should be able to do this, but neither is working. Both depend on zlib for this functionality. I have tried reinstalling zlib, but to no effect, and it cannot be removed and reinstalled due to dependencies.

I am running Ubuntu 7.10. I use Gnome, but can't find any viewers for it that can browse zips like ACDSee can, so I use KDE ones instead.