We've created a short animation that has audio throughout, and when played in Flash player it syncs up with events etc. fine - but when played in a browser the visuals are about 6 seconds behind the audio. Is this a pre-loading issue?... any ideas?

Thanks

This is most likely an issue with your sound set up as an 'event' and not a 'stream'.
An 'event' based audio clip will play on entering the frame, and play back independent of the animation. Therefore, performace of your computer or internet connection could slow it down. When it's set to 'stream' the audio will synch up to the animation.

However, it is always a good idea to preload any animation or audio that's going to play so that you can minimize viewers seeing missing graphics or not being able to load audio.