Postsharp Unhandled exception simply by adding a reference

I started playing with Postsharp but cannot get past the first step. Someone else reported on their forums at http://www.sharpcrafters.com/forum/Topic4817-18-1.aspx but was wondering if anyone has come across this and perhaps have a solution.

Am using VS2008 and have .net3.5SP1 installed.

(Posting here as there is more activity than their forum).

POSTSHARP : postsharp error : error: Unhandled exception (2.0.6.1236, 32 bit, CLR 2.0, 
Release): Object type cannot be converted to target type. See below for details.
POSTSHARP : postsharp error : System.ArgumentException: Object type cannot be  converted to target type.
POSTSHARP : postsharp error :    at System.AppDomain.DoCallBack(CrossAppDomainDelegate callBackDelegate)
POSTSHARP : postsharp error :    at PostSharp.Hosting.PostSharpDomainManager.CreateDomain(String friendlyName, Evidence securityInfo, AppDomainSetup appDomainInfo)
POSTSHARP : postsharp error :    at System.AppDomain.CreateDomain(String friendlyName, Evidence securityInfo, AppDomainSetup info)
POSTSHARP : postsharp error :    at System.AppDomain.CreateDomain(String friendlyName, Evidence securityInfo, AppDomainSetup info, PermissionSet grantSet, StrongName[] fullTrustAssemblies)
POSTSHARP : postsharp error :    at PostSharp.Hosting.DotNet.DotNetPlatform.CreateAppDomain(String _0, Evidence _1, AppDomainSetup _2, PermissionSet _3)
POSTSHARP : postsharp error :    at PostSharp.Hosting.PostSharpObject.CreateInstanceInPrivateAppDomain(PostSharpObjectSettings settings, IPostSharpHost host)
POSTSHARP : postsharp error :    at PostSharp.Hosting.PostSharpObject.CreateInstance(PostSharpObjectSettings settings, IPostSharpHost host)
POSTSHARP : postsharp error :    a开发者_JAVA技巧t PostSharp.Hosting.Program.ExecuteImpl()

I have answered on http://www.sharpcrafters.com/forum/Topic4817-18-1.aspx.