Why does Web developer built-in web server only server 0 byte files suddenly?

[mrc22091]

Visual Web Developer 2010 Express. C#, MVC3.Clicking F5 to debug.It starts up the built-in ASP web server on \[code\]http://localhost:50188/\[/code\]The Output window tells me WebDev.WebServer40.EXE is loading loads of DLLs.Up until yesterday it worked. Today all URLs give me a blank page!All controllers (all that changed yesterday was one controller, and some of its views). Same results in two different browsers. Use a different port gives an error (Telling me that there is something listening on port 50188!!) No errors anywhere. Just 0 byte files received.My question is What happened and how do I fix it?More Info:Rebooting the machine made no difference.I also found the obj/Debug directory and deleted it. It got recreated next time I hit F5 to debug. Still exactly the same problem!