Render using Mitsuba GUI; load {FileStream] Error while trying to open file

[musm]

See:
http://imgur.com/a/B6KYt
This is what happens on a default Blender scene when I change the "render using" to Mitsuba GUI instead of Mitsuba Console
Blender 2.78

Read new prefs: C:\Users\Mus\AppData\Roaming\Blender Foundation\Blender\2.78\config\userpref.blend
found bundled python: C:\Program Files\Blender Foundation\Blender\2.78\python
Register
[Mitsuba 2017-May-04 18:36:48] Installed scene post-update handler
0 meshes freed
[Mitsuba 2017-May-04 18:37:26] WARNING: Binary mitsuba module not available! Visit http://www.mitsuba-renderer.org/ to obtain one for your system.
[Mitsuba 2017-May-04 18:37:26] (ImportError was: No module named 'mitsuba')
Frame Change 1
[Mitsuba 2017-May-04 18:37:29] INFO: Creating Mitsuba context
[Mitsuba 2017-May-04 18:37:29] Scene File: C:/Users/Mus/AppData/Local/Temp/untitled.Scene.00001.xml
[Mitsuba 2017-May-04 18:37:29] Mesh file written: C:/Users/Mus/AppData/Local/Temp/untitled\Scene\00001/Cube_0000_m000_0_000000.serialized
[Mitsuba 2017-May-04 18:37:29] Wrote scene files
[Mitsuba 2017-May-04 18:37:29] C:/Users/Mus/AppData/Local/Temp/untitled.Scene.00001.xml
[Mitsuba 2017-May-04 18:37:29] INFO: Export finished
[Mitsuba 2017-May-04 18:37:29] Starting Mitsuba
[Mitsuba 2017-May-04 18:37:29] Launching: ['C:/Program Files/Mitsuba 0.5.0/mtsgui.exe', '-o', 'C:/Users/Mus/AppData/Local/Temp/untitled.Scene.00001.png', 'C:/Users/Mus/AppData/Local/Temp/untitled.Scene.00001.xml']