I found a strange problem recently. Using Gallery I could always upload new pictures but someone else using Vista could not upload any pictures. It didn’t matter if she used IE or Firefox, every single upload made Gallery come up with error #2038 (IO). I could say that anyone that uses Vista deserves everything they get, but that would be a little churlish (if true).
A few searches showed that this basically gallery saying “something bad happened with your upload”. No, really? You mean it’s not supposed to be a big red box and no uploaded file? It’s not the world’s most useful error message.
What got me onto the right path was a message on the gallery forums though it was the other way around. Gallery uses a flash uploader which and this is the same flash if you use Firefox or IE. It seems it doesn’t like “strange” SSL certificates, such as chained certificates like that site uses (and my site too). No doubt there is probably some work-around or setting to fix it, but being Vista its probably buried in 20 menu items under some obscure reference.
Setting up the gallery under a non-ssl site fixed it. Perhaps more correctly it was a work-around.