Oddly, in some ways it looks like the bug involves a race condition. Some of the time, the image will partially display, up to some fraction of its height. This is rare -- most of the time Mozilla presents a "broken image" icon instead.
The first two images don't display in Mozilla under windows. The third image is just a re-formatted version of the second (opened and then saved in an image editor); the re-saving process changed the internal structure of the PNG enough that Mozilla is able to display it.
The last IDAT chunk in this file has a length of 1:
The last IDAT chunk in this file has a length of 3:
The last IDAT chunk in this file has a length of 10:
November 2002: this bug is fixed. Check bugzilla for details.