What he said.
If you're using an AMD graphics card and have recently updated to the latest Catalyst driver, then you'll have a problem seeing some rigged mesh.
A workaround is to untick 'Hardware Skinning' in the graphics preferences, and that should fix it. It did for me.
If it is related to the AMD card, then the other option is to roll back the drivers to Catalyst version 14.4, as that seems to be the most stable.