Possible bug?

Has anyone else ever encountered a situation in flash where clicking a button or performing some kind of action, causes certain elements on the stage to move slightly, by a pixel or so. It’s currently happening in a project I’m working on and it’s frustrating the hell out of me. Anyone know of any ways to prevent it?

And yes, I have made sure the items in question are positioned exactly to the pixel, rather than at something like 34.9