Sprites randomly appearing

Hi.

Im am currently creating an interactive CV for a university project.

I'm having trouble with some spirtes that quickly appear when I go from certain links to ceratin destinations. If i go from one section back to another, a sprite that has nothing to do with either of them quickly appears half way through the transition but is not there at that point on the timeline. I have no idea why and it is really frustrating me as the project is due in on monday.

If you have any idea why this is happening, please help me.

Thanks