In Visual Studio,

• go to Debug|Windows|Exception Settings, make sure that it will break on "CLR Exceptions" and "Managed Debugging Assistants"
• start your application under Visual Studio Debugger
• when exception in Dispose occurs, Visual Studio Debugger will stop
• go to Debug|Windows|Call Stack, you will see who was calling whom. You can also double-click on the line in the Call Stack window. This will bring you to that line in your code, and you will be able to see all variables visible in that particular stack frame.