I have a solution in VS 2008 that consists of multiple Asp.net Web applications. Every time I start a new instance of any one of them, all of them open up ports on the development server and the system tray is littered with asp.net development server icons.
This never happened in vs 2005, only the web app that an instance was started of, comes up. How do I stop all the web apps from opening ports in vs 2008?
Try using the File -> Browse Website instead of running the solution.
There are two types of web projects in VS2008, Web Sites & Web Applications. I tested this with a Web Application (though, they maybe the same). I have two web-sites in one solution, and as you stated, two IIS ports opened up. Here's how I fixed it.
Click on the web-site in the solution explorer and then view the properties for it. If it's a Web Application it should have a property called "Always start when debugging". Set that to false for all web-sites you don't want to start up when you begin the debug process (e.g. click play).