Flash CS5.5: Problems with cartoon creation - any added motion slows down timeline

I'm creating my first cartoon in Flash CS5.5. I have a character rigging created that has a body symbol with a head symbol inside that. The mouth movements I created in the Head symbol sync up to the sound until I add any type of motion to the main stage or to any symbol. Once motion is added the time it takes to get through the timeline is stretched by a noticeable amount and the voice and action gets out of sync. I don't know what I am doing wrong. I did change the from 24 fps to 30 half way through the creation. Not sure if that screwed things up. This problem first showed up when I used the bone tool.