MXF Playback on timeline only playing 3 frames at a time!!

Ok so this is a strange problem. First off Im playing .MXF files in FCP7 with a Calibrated plugin (great plugin btw) anyhow after merging my separate audio and video files together I put them in the timeline.

Everything works fine up until this point.

Now whenever I play whatever is in the timeline, Final Cut will only playback short 3 frame bursts then it pauses. I have rendered everything and when I export to a quicktime reference the sequence plays back perfectly. What am I doing wrong to make it playback like this?

Thanks!