The model contains characters that cannot be encoded with the model's character encoding 'windows-1256'

Matlab 2009a, when saving a simulink file, even an empty file the follow message shows:-

The model 'untitled' contains characters that cannot be encoded with the model's character encoding 'windows-1256' Either
1) Change the character encoding setting of the model, by using: 
set_param('untitled','SavedCharacterEncoding','windows-1256',or
2) identify the characters that cannot be encoded and remove them from the model, the first unsupporster character occurs on line 23, bye offsett 15 in the  file...untitled.err

[Walter Roberson]

What is your home directory, or the directory you are saving into?

[Walter Roberson]

(Windows 1256 appears to encode Arabic)

[Walter Roberson]

This may sound odd, but exactly what Username are you using for your account?

It looks to me that if your username was not representable in the character set that you have active, windows-1256, that you could run into that error message when you attempted to save any .mdl file.