Please, help me.It's urgent!
Just not enough information.
How did you create the animation/Flash doc. The more exact details the better. How much actionscript is used? etc.
Are you using MAC or Windows? If you could zip the files up or post a link to it, I could take a look at it to figure out what the problem is.
Check to make sure you don't have an extra scene in your Flash document. The white flash could be if you have an extra scene with a single empty frame.