We had a page named "Håndjern" (note the danish letter 'å' in the title).

When we added an attachment such as an image to the page, and then tried to display the image in the page, the image appears broken and could not even be downloaded from the attachment list - it's as if the attachment was not there, even if it appears in the attachment list.

When we changed the name from "Håndjern" to "Haandjern", the problem went away and the attachment was displayed normally.

Since it's a quite normal thing to have danish pages named using danish characters, this is a major problem for us.