Request for principal permission failed

I just upgraded our solution to .NET 4.0 from 3.5. Now, when I run on my local machine I get the error in the subject with the follow stack trace:
[SecurityException: Request for principal permission failed.] System.Security.Permissions.PrincipalPermission.ThrowSecurityException() +3063281 System.Security.Permissions.PrincipalPermission.Demand() +419 System.Security.PermissionSet.DemandNonCAS() +117 Default..ctor() +46 ASP.default_aspx..ctor() in c:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\portal2\cd038864\2f003115\App_Web_nnaicimo.1.cs:0 __ASP.FastObjectFactory_app_web_nnaicimo.Create_ASP_default_aspx() in c:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\portal2\cd038864\2f003115\App_Web_nnaicimo.7.cs:0 System.Web.Compilation.BuildResultCompiledType.CreateInstance() +30 System.Web.Compilation.BuildManager.CreateInstanceFromVirtualPath(VirtualPath virtualPath, Type requiredBaseType, HttpContext contex ...