ASP。NET MVC / IIS 7.5:只有静态内容的内部服务器错误为500

An ASP.NET MVC project running under IIS 7.5 (but problem may exist on earlier versions and non-MVC sites) which was previously working has started returning 500 Internal Server Error but only for content handled by the static handler - images, pages etc. handled by MVC itself through a controller work fine. An ASP.NET MVC project running under IIS 7.5 (b