Animate banner running different start everytime it runs

Hi I have a banner running on a site where it is shown in 10 sec and then another banner is shown. I have an animation that is 10 sec but when this banner is running it runs fine the first time but next time it is showing some of the last part of the animation. The 3rd time a different way it is shown and the it runs rigt again.

How can i make my banner/animation always run from the start. I belive it can be something with the internet connection or ? Bu I would like to make sure that my banner runs from start everytime it is shown..

Any ideas please

Thanks so much

Lars Gravesen