"And that is why, in 2009, when developing in Microsoft .NET 3.5 for ASP.NET MVC 1.0 on a Windows 7 system, you cannot include /com\d(\..)?, /lpt\d(\..)?, /con(\..)?, /aux(\..)?, /prn(\..)?, or /nul(\..)? in any of your routes."

Source: http://news.ycombinator.com/item?id=655397