It's probably similar to this:
hub.virtamate.com
Check the thread for the fixes.
Freezing Model issues with RT_LipSync - All but hair and heels
Apologies at the repost from 'Plugins' but I think I may have put it in the wrong area. I see this Help area is probably where I should have started. Note: I have since seen that there were others having this issue, but I havent seen any follow ups on whether or not they got it resolved. Any...

Check the thread for the fixes.