onEnterFrame: randomly choose [pre-programmed] mc position after setInterval--problem

Hello everyone.
First I would like to say that I have learned an immense amount from all of you on this forum and would like to thank everyone for their participation in this community. That being said, I was hoping that someone could give me a code hint, or point me in the right direction regarding my AS prob.

[now for the setup]
I have a mc (named: imageHolder) with 4 nested empty mc (named: container1, container2, etc). Each of these dynamically load a jpg. [so far this all works great] Each of the containers are at specific locations inside of imageHolder [ex: container1 is located @ 0,0; container2 @ 600,0; container3 @ 0,175; container4; 600,175]. The point is… These 4 images are different background images.

[The question is this…]
I would like to randomly choose from one of the backgrounds, then move to it after a predetermined amount of time [using setInterval]. [so the effect is the background constantly panning around].

I am using an easing menu system in another area for this particular site, so i know the code to make something similar work onRelease, but i want this to choose one of the 4 mc [container1-4] and move to it [and stop there for…say 10 seconds] randomly, then move to a different clip.

i hope that this was descriptive enough, please let me know if you need more info or anything at all from me. I would like to thank anyone in advance for viewing/helping me with this problem!!!