FLV Playback BUG!

I have just built a Flash Slide presentation. There is a navigation bar down the left side that calls different slides. The slides either have a static graphic on them or the media display component that calls an flv file. This all works fine but when an flv file plays through for the first time it flies through it like a bat out of hell! I mean it plays the video file (say 2 min length) in about 40 seconds. Once it has played through once, if you hit pay again the flv file plays at the correct speed. This happens for all of the video files.

Would anyone know why this is?