>>Check if this discussion may be of help
>>http://stackoverflow.com/questions/146134/how-to-remove-illegal-characters-from-path-and-filenames
>
>Thanks, but the goal here is not to change the file name as it is a perfectly legal Windows file name. However, in the basic functionality of Response.AddHeader() Content-Disposition parameter, this only accepts US-ASCII. This is where the problem here. The file name "My file à name.txt" is legal Windows file name. And, I name to have that file transmitted as is to the client across the browser.

partly fishing:
client and server set to identical locale ?