Running an ArcGIS Engine application on a 64-bit platform causes the following runtime error message:
"Unable to load DLL 'ArcGISVersion.dll': The specified module could not be found. (Exception from HRESULT: 0x8007007E)"
This runtime error occurs when the platform target for the ArcGIS Developer Kit version 10 or 10.1 application is set to 'Any CPU' or 'x64' mode when compiled. This creates a header file in the application, instructing the Common Language Runtime (CLR) to load and run the executable in the same process space in which the application is run. Therefore, when the application runs on an x64 (64-bit) machine, the 64-bit process cannot load the ArcGIS Engine DLLs marked as x86 (32-bit).