Flash CS5 - Unwanted bitmap displayed in background that appears not to be on stage

I'm building a flash "rotating banner" for a website (where there are 4 slides that automatically move on from the one to the other after a few seconds and repeat indefinitely - these slides can also be navigated by 4 little buttons). The problem I'm having is that when published into the html and I refresh the page, I can see the bitmaps that I used to create the buttons appear in the center of the stage (as if it was behind the first slide).

This however is not the case, I've gone through every layer and every single movie clip and cannot find these bitmaps embedded onto the stage in any way.

I used Cntrl + B (Break) to break apart the bitmaps and then used only parts of the bitmaps to create the 4 buttons. Could this have anything to do with this problem?

All pixels on stage have been converted to Movieclips.

If anyone knows what the problem here is, please help! I need to fix this, I need to get it to stop displaying the bitmaps on refresh, it has to be perfect.