restart of web dev server every time load ASP.NET MVC application

I continously get this problem (stack trace below) when I start my ASP.NET MVC application and have to restart the web dev server and then it goes away. It appears to be happening on when I make modification in my jquery and then try to restart the application.

protected void Application_Start()
        {
            InitialiseIocContainer();
            RegisterViewEngine(ViewEngines.Engines);
            RegisterRoutes(RouteTable.Routes);
            SetupLogging();
        }

It appears to get caugth on the Application_start in global.asax. I've done lots of search in google but no luck. ITS DRIVING ME BONKERS!!!!

can anyone help please

Server Error in '/' Application.
--------------------------------------------------------------------------------

Loading this assembly would produce a different grant set from other instances. (Exception from HRESULT: 0x80131401) 
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.IO.FileLoadException: Loading this assembly would produce a different grant set from other instances. (Exception from HRESULT: 0x80131401)

Source Error: 


Line 30:             RegisterRoutes(RouteTable.Routes);
Line 31:             SetupLogging();
Line 32:         }
Line 33: 
Line 34:         private void SetupLogging()


Source File: C:\UserData\SourceControl\LLNP4\Trunk\Web\Global.asax.cs    Line: 32 

Stack Trace: 


[FileLoadException: Loading this assembly would produce a different grant set from other instances. (Exception from HRESULT: 0x80131401)]
   LLNP4.MvcApplication.Application_Start() in C:\UserData\SourceControl\LLNP4\Trunk\Web\Global.asax.cs:32

I would say it has to do with the SetupLogging() method. Does the user account that the site is running under have read/write access to the file path where you are storing the logs?