Images getting shifted and wrapping on themselves...?

Hi All,

I have written an application to read FITS files. I now have an
anomaly where some images have a "split" in them. Basically it
appears that the image is shifted to the right or left by so many
pixels and "wraps" around. This doesn't happen, however if I open it
in GIMP using the FITS plugin, or with various other FITS Viewers.
I'm curious as to what could be happening. Is there some type of
"key" in the data that would tell me about a particular offset? I've
checked headers between "good" files and the "split" ones and there
seems to be no relevant differences. In fact, most of the split
images only have SIMPLE, BITPIX, NAXIS, NAXIS1, NAXIS2, and no other
data.

Any input would be most appreciated.


Best!