Language again again.

Hi all.

I have a somewhat strange problem with winXP

I've bought a Dell Dimension 9150 with Win XP Media Center Edition
Now for the strange part.
The installation (recovery) of windows XP is in english, and during install
I choose Danish as the language for windows.
After install Windows was running fine with Danish GUI.
I then had a problem with a program and had to reboot in failsafe mode.
After I then rebooted the computer XP had changed the language to english!
In the regional and language settings everything is set to Danish, but alas,
no luck my windows is still insisting on displaying everything in engilsh.

I've read, all over the web, that it is not possible to change the language
layout of WinXP without buying a win version in the desired language, but
never the less that is what have happened to me.
An english WinXP started displaying danish and then switched to english.
So somewhere it must be possible to change the GUI back to displaying danish
but how and where.
Anyone who can help med find out how to do it with out the need to reinstall
everything once again?