I just answered this similar question, and i think the same should apply in this case: Visual Studio Development Server (Cassini) does incorrect routing for dots.
If you create a file system Web site in Visual Studio 2010 and the Web site is in a folder that contains a dot (.) in the folder name, URL routing will not work reliably. An HTTP 404 error is returned from some virtual paths. This occurs because Visual Studio 2010 launches the Visual Studio Development Server (Cassini) using an incorrect path for the root virtual directory.
There are 3 workarounds, and only the "use IIS instead of Cassini" workaround seems to work for ServiceStack.
The problem will go away if you edit your project Web properties and check "Use IIS Express" instead of "Visual Studio Development Server".
The cases to use IIS Express are explained in the announcement, and there is a download link.