Recently we have quite a lots of problem from some of our users with MPI.NET. The problem is, yet again, .NET framework keep asking about whether to trust the program to run in the Cluster. The running program pop-out exception regarding permission always. The thing is, compute node should be trusted all times.
To fix this, see following threads.
Security Exception with MPI .NET - Windows HPC (High Performance Computing) forums
The trick is the "caspol.exe" command shipped with .NET.
