I often use a Windows XP box for development (yes, I know I need to upgrade but it still works pretty darn well for me) and I ran into an issue I’ve seen before when setting up a test MVC application recently. To run an MVC application on IIS 5.1—the version of IIS on XP—you must set up a wildcard mapping extension to allow extensionless URLs like those typically used with ASP.NET MVC to work.

This procedure is straightforward except…you can’t save the new mapping! Even after setting all the values in the dialog box, the OK button is still disabled and grayed out. This is a bug in Windows XP and you can find the solution at http://support.microsoft.com/?id=317948. It’s a small thing but should save you a couple of minutes of googling if you are setting up a new MVC project on Windows XP.