One of my programmers recieved this error message while he was working on anASP.NET 1.1 project:
Unable to start debugging on the web server: The system cannot find the file specified
Strange thing was that a moment ago everything was working fine, the project was running in IE with no issues at all when suddenly this error message cropped up.
I told him to register ASP.NET with IIS again using aspnet_regiis -i at the VS comman prompt. But this did not help.
Then I accidentally noticed that his IE had Work Offline selected. I removed the check against Work Offline and voila, the project started running just like before!
Hope this helps!