One of the things that can drive you crazy is aiming for cross-browser compatibility. Usually the problem is that things look wrong.
But sometimes the problem is that something you can see fine in one browser is simply invisible in the next. Looking at source confirms that both browsers are seeing the same code — one is just not doing anything with it. Drives me nuts.
So it’s very good to at last have an answer that I’ve found a known bug: IE just can’t handle some .png images. It was hard to debug because it can handle others. But IE cannot handle all .png images. Sometimes IE does not display .png images at all. Yes, there is a bug in Internet Explorer and it does not display some .png (‘portable network graphics’) files.
(I’m saying this very pedantically so that the next poor guy who has to hunt for this on Google has an easier time of it.)