Working on an ASP.NET Project (not Web Site) and trying to Start without Debugging from Visual Studio.
First this:
Then this:
Once completely reinstalled Microsoft Visual Studio 2008 and it was fixed... for a while.
Looking for any information I can find, including:
Try this - shouldn't take more than a minute or two.
Create a brand-spanking-new, empty Web Application Project. Enter something like "hello world" on the default.aspx page. Run it.
If your problem disappears, you've got something (3rd party DLL, etc) referenced in your project causing the issue.
Else, your looking at an OS, IDE or other environmental issue. I've had some odd VS issues in the past on Win7 that were solved by available updates. I still have to run VS as an administrator to use the "attach to process" for debugging.
update
So, the new project works, which tells us that the problem is somewhere in your old project. This is where the fun part starts, which is what I like to call "binary search debugging." It's crude, a pain in the ass, and if your app is pretty complex, sorting out dependencies can be a pain in the ass.
Create a new project and add all of your source to it.
Build, run. Did it work?
No? Remove half of the source.
Build. run. Did it work?
If so, the problem is in the half that you removed.
Else, it's in the half that remains.
Now, I know this is an incredibly naive approach to debugging, and its very brute-force, and some app configurations can make this damn near impossible, but at least its straightforward.
Any other service listening to the port number you're using? Try changing the port number or use IIS instead of running it on cassini.