What to do if you receive the System.Runtime. InteropServices.COMException error in Visual Studio 28. January 2008 Reviews Comment (4) Hi everyone,I prepared some new exciting blog posts, especially about XNA and I will post them shortly and also quite a few things will change at this blog. Stay tuned.Recently one of my companies (namely realis) moved to Hamburg and I have a new PC at the new office, where I installed Visual Studio 2008 and everything else I needed. After I downloaded the latest source code files from Team System, I ran into some problems. BTW: The Team System trial will end next month and I will probably not switch back to SubVersion, but instead go back to Visual SourceSafe since the integration is the best in Visual Studio. Team System is nice to have but absolutely not something important for me as I'm most of the time the only guy using it anyways.Back to the Problem. After I loaded the main solution the 2 web applications in it were unable to be loaded. The rest of the projects did load fine and worked after a while until I had all the missing Assemblies installed (xunit, Ajax stuff, Silverlight, IronPython, EntitySpaces, etc.). But even after making sure Silverlight and the Silverlight Tools for Visual Studio Alpha was installed and working (checked it by creating a new Silverlight project, which worked fine), I was still unable to load those projects. I thought at first maybe something went wrong when I checked in or out all the files, but after testing it on my laptop this was not the issue, all files are intact. Everything worked just fine on my laptop, where I had done most of my work during the move and first weeks until everything was finally working here.After digging around a bit I went back to the IIS were those 2 websites should run on and they did not run yet (not compiled yet, no wonder). But even after I pointed to some dummy website the IIS did throw out some errors (first some dlls were missing, they were quickly replaced, then some security issues with Vista, also easy). Then I pointed back to the location of the projects and made sure IIS was working this time. Now I could go back to Visual Studio and finally load the web projects.If you have such a InteropServices.COMException, try to see if you have missed something like the Silverlight Tools for Visual Studio Alpha and then figure out if your IIS is working. You can also edit the .csproj file and remove the references to IIS at the very end of the file to see if the project can then be loaded (using IIS again is not hard through the project properties).Hope this helps (phase stolen from ScottGu, btw: really cool stuff going on over there, the ASP.NET MVC framework is nice and the .NET Framework SourceCode is very helpful!)