I have found and fixed the problem.

I don't have access to the most recent version of the code right now, so it'll be over a week before I'll be able to put up a new version. In the meantime, convert all 7-bit and 8-bit PNGs to another compatible file format. 1-6 bit PNGs should work fine.

If there are any other bugs anyone has noticed, always feel free to tell me about them. Telling me during the next 9 days would be nice, though.

P.S. This thread should probably be moved to JCS...