Here I explain you to solve the System.Runtime.InteropServices.COMException which prompts while opening the project in VS2008.
Fixing the error
This error occurs when you are using the System.Runtime.InteropServices in your project.
To solve the problem:
First check the IIS Settings for your project by mapping the project folder correctly to the IIS website.
Open the Microsoft Visual Studio 2008 in Administrator mode.
Now open the project in the vs2008
Build the project and Run.