Past Post:
http://www.zenphoto.org/support/topic.php?id=3829
Okay well, I dunno the problem, but I do believe new versions of zenphoto is taking up too much memory...some how, even modifying the php.ini file doesnt work (for me)...
I insisted that it did work in the past but not anymore..
GO HERE:
http://luckyshotphotos.com/zenphoto2/test/IMG_3828.JPG.php
Download the file, upload it to the latest zenphoto and see if its too big for you... It wont work for my current version (nightly build) last night
I went down the nightly build list and downlaoded an older version (randomly picked) and it works...
So... I am keeping this version

zenphoto version 1.1.6 [1567]