you are using too much ram on a windows 32 bits system, I'm pretty sure the trouble is that one. About log file, your xml is correct. Nebula generates a file named nebula3.log in your nebulatemprepository. Maybe "log" extension is hidden for somewhat reason. Or you turned UAC on, so it can't write there!
Confirmed its RAM Problem. I did the "3GB switch" trick that enables to use more ram and finally the nebula loads. Before I couldn't create the log file because the plugin couldn't load properly and its GUI wasn't appearing, instead a generic steinberg gui with faders was shown. Now it possible to create the log file but I guess I don't need it since the problem is resolved.