If I search for a word containing a Swedish letter like å ä or ö (this is probably true for all non-English letters), like if I use this search query:

"Går även att"

That returns this error:

The following words in your search query were ignored: G r ven att

See? The letters were just taken out. I don't know if it actually removed them from the actual search or it's just from the HTML display.

Apache version 1.3.37 (Unix)
PHP version 4.4.4
MySQL version 4.0.27-standard