MacBook pro with M-audio recording interface. LP 10.2. I'm trying to add harp parts to a track sent by my bandmate. Each successive take shifts 1 beat out of synch. I have to keep moving the master track to the right to line up on playback. Driving me crazy. Does not happen every time - sometimes recordings are just fine no matter how many takes. Have rebooted LP and the macbook and started a new project when this happens, but I never know when it will work or not. Please help - driving me crazy.