From LightWiki

Bone rest positions (the location and rotation of a bone inside your character when the character is not deformed (ie. 'at rest')) sometimes do not behave themselves when you load a scene. Your character can appear to 'explode' or rip itself apart when it is loaded back up in Layout, even though your bones appear to be correct.

At this stage, do not panic! Your file is not corrupted - The bones simply need to be reminded of their rest details. Doing this is relatively simple...

Go through each of the bones in your character and hit the letter "r" on your keyboard for each one. Now save and reload the scene.

Note that you can also select ALL bones using one of LightWave's methods (via Scene editor selection, Shift-Click selection on each bone in the viewport, or Middle-mouse button(wheel) click and drag a selection marquee). Once selected, press "r" to rest all the bones at the same time if you prefer.

Caution: Do not rest bones on frames when they have been posed or animated. This will create no end of headaches as the character mesh resets to its rest position while the bones appear to live outside the object.