Worked out what's messing the fingers up

[Domarius]

I suppose this only applies to everyone working in MotionBuilder (me) but anyway;

 

Seems that sometimes, randomly, whenever you move the hips with Full Body Mode selected, the fingers on the left hand will snap upside down.

 

I still don't know what's actually causing this but it's very easy to fix - just find the key frames it's occouring on, select body part mode, select the fingers, and delete those keyframes for the fingers. Going to body part mode like this will leave the keyframes for the rest of the body parts and only delete the keyframes for the fingers.