>>319151160
It takes 2 seconds to fix and you can fix it on any version you downloaded. Just check the read/write enabled box. 
It probably doesn't actually cause it to be 2 billion polys. My completely uneducated assumption is that because it can't "Read" the information on tri count from the .fbx it's just assuming the worst and defaulting to the maximum possible polys allowed as the tri count value.