Are you running a release or compiling from source code?
We aren't having these issues at all.
You may need to set UseCultureOverride to false in the web.config to use Arabic, or set it to true and set the site1culture and site1uiculture to "ar-DZ". Full list of codes here. <<--EDITED
Whatever you do, do not delete the English resource files. These are the defaults so if your chosen culture doesn't have something, .net will fall back to the English files. If you remove the English files, there is nothing for .net to fallback to and it will cause errors.