help with special characters in url Profile

I have the following problem: symbol ø

I have a user who was registered with the following name

http://www.notwall.com/brianfløe

this symbol is ø

 

then I have the following error

 

Not Found

The requested URL /brianfløe was not found on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.