I got this error after updating Microsoft Visual Studio 2008 Service Pack 1 (which took much longer than expected - close to two hours):
WebDev.WebServer.exe has stopped working
Unable to connect to the ASP.NET Development Server
As usual, this appeared to be a problem many people had, under many different scenarios, with many different solutions. The following solution is the solution that worked for me:
Delete the web project from the solution, rename the folder where the website is stored and then re-add the project to the solution as an existing website.
This is fine on my local laptop, but would probably be a bit more disconcerting in Visual Source Safe.
So my best guess is Visual Studio stores information about a web site somewhere. If you don't perform the folder rename, when you add the web site back in you'll see the original, dynamic port settings. It appears renaming forces a new port.
I don't know where this information is stored. I can't seem to find anything in the registry, and deleting the temporary asp.net files didn't have any affect.
Although renaming the folder worked, I also did this:
The host file at %\Windows\System32\drivers\etc\hosts may have an incorrect entry. This line...
was changed to...
That's three colons - not two.
I didn't experiment any further and have just moved on.