物理文件夹在IIS Express上中断ASP.NET URL路由

IIS Express is producing 403.14 Forbidden errors when a URL that would otherwise be handled through ASP.NET URL routing happens to correspond to a physical folder in my ASP.NET project. (The folder contains only code, and it's coincidental that the folder name happens to match the URL of a page; my URL structure is determined dynamically by a database, and users can edit that structure, so although I could just rename my project folder, in general I can't prevent this sort of collision occurring.) error