Foreign letters in guestbook .txt file? Urgent help!

I have a little guestbook made with Flash, a .php file and a .txt file.
I came across a problem with it displaying the three extra Danish letters, Å Æ and Ø.
I have used the guestbook before on another site and was able to fix the problem, but this one just won’t seem to work.

Yes, I’ve embedded the font…
Yes, I’ve saved the .txt file as Unicode (have also tried UTF-8)…
Yes, I’ve put System.useCodePage = true; on the first frame…

I need some help, and I need it urgently! Many many thanks to anyone that might have some suggestions.