This has been discussed here before and please file a ticket to SM with all the details.
The more information they have the faster a fix can be found.

On a deja discuté de ce pheneomene ici.
Rapporter vers SM avec tout les details possible, Le plus d'info ils recoivent le plus vite ils trouverons une solution.

Reference;
http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2837161

@BB it is not prop sensitive
It "randomly" happens to figures, masks, props, even the sphere.
You know where to find the details.

Poser 1, 2, 3, 4, 5, 7, P8 and PPro2010, P9 and PP2012, P10 and PP2014 Game Dev
"Do not drive faster then your angel can fly"!