This is not my first app running on the client location. My other apps are .Net 3.5. No problems putting our CR reports in those apps.
This app I did in VS2010 using 4.0. Of course, CR was not included, which led me down this long, horrible road. I have been spending all week getting CR to work in my .Net 4.0 app.

On the client machine where this is dying, you're saying that on the same machine, someone has been able to run CR reports from .NET 3.5?

I'll keep thinking....maybe someone else here has an idea....but something tells me this is something with the environment. (That would possibly explain the error message not being helpful)