Encoding confusion: most odd!

[wisam]

On the office website there's a search form in the middle of the page. The site itself is using ISO 8859-1, for historical reasons. The search application, a Java app, uses UTF-8, so the search form has an accept-charset="utf-8" attribute.

We have serious trouble when searching for phrases that includes non-ASCII characters, like the Swedish letters, 'å', 'ä', 'ö'. For testing purposes you can try searching for 'grön' (means 'green').

In Opera, everything works just fine.

In IE7, the first search is fine, but all subsequent searches with non-ASCII characters fail. Instead of 'grön' the search box on the result page shows 'gr�' (the last character is U+FFFD, i.e., the Unicode 'replacement character').

In Firefox (we're stuck with 3.0.7), Safari and Chrome, the first search fails if it contains non-ASCII characters, but all subsequent searches work. In this case the result page search box shows 'grön', so it looks like UTF-8 that has been interpreted as ISO 8859-1 and then encoded as UTF-8.

Does anyone have any ideas what could be going on here? Or should we just try to convince the rest of the world to use Opera once and for all?