This is a known issue, and results from differences in the way VS 2010 and VS 2010 sp1 use some registry entries. This will be fixed in the upcoming JNBridgePro 6.0 release, and we also hope to provide a patch for JNBridgePro v5.1. In the meantime, you can continue generating proxies with the JNBridgePro standalone proxy generation tools. Any .jnb (JNBridgePro project) file that was generated using the Visual Studio plug-in can be used with the standalone tools.