Webdav gives 404 error, when trying to publish/read on a domain/subdomain with IFN format (xn--)

This error happens both with Microsoft FrontPage as well as with Microsoft Expression 4.

As long as the domain/subdomain is a normal one, everything works fine.

If however, I have a domain/subdomain like xn--konomi-9xa.as-norge.no, I can connect as usual, but when I say try to publish,
I get the following error:

404 - File or directory not found.
Server Error 404 - File or directory not found. The resource you are looking for might have been removed, had its name changed, or is temporarily unavailable.

Any idea(s), in how to resolve this?

Thanks :)