The Log.txt does not indicate the specific reason for why X-Plane quit. However, this line in the Log.txt file is a hint as to what the reason probably is...
"SkyMaxx Pro: WARNING! CPU free memory at 33148 KB. X-Plane may crash due to lack of memory. Close other applications, reset your settings, or remove memory-intensive add-ons such as photo-scenery."
Meaning... you are exceeding your hardware memory limits.