In xcode4, (I have used v4.0.1 until now and downloaded v4.0.2 yesterday.) I made Localizable.string files and compiled my project. (As you know, my source code uses NSLocal
Looks like this is an standard message for error reading the strings file.
In my case it was a (json force of habit) colon instead of equal sign:
"key1" = "String1"; "key2" : "String2"; "key3" = "String3";
Changed it to = and everything worked fine.
=