Unable to launch the ASP.NET Development Server because port ‘n’ is in use.
This error displays itself when trying to debug a Web Application or Web Service project from within Visual Studio 2005 and/or Visual Studio 2008 on machines running ESET NOD32 Antivirus. This problem seems to occur every couple of months on our team, and for some reason we always go round and round trying to troubleshoot it, even though we’ve seen the fix numerous times, so I’m documenting it here again.
Double-click the NOD32 Antivirus link in your system tray. Highlight “Setup” in the left pane and click “Antivirus and antispyware”
Click ConfigureU under Web access protection (see image above).
Select “Antivirus and antispyware” –gt; “Web access protection” –gt; “HTTP” –gt; “Web Browsers” Find all of your devenv.exe instances in the list and click the check box next to them until a red x appears ( ). Note: DO NOT make the box checked ( ) or the issue will continue!
Click “OK” and close NOD32. You should now be able to launch the ASP.NET Development web server again without issue.