I think we all have the ‘SHAK’ thing down…
What Bubba said; When you make a movie clip [MC] there is a place to put stops in at the end of your timeline in the actions panel. normally you would highlight the last frame where you want a stop, then pull up your actions panel, and then choose STOP. Just don’t do that. And it will keep looping.
And to save you time with the Q’s your about to ask, oh, say around 10pm this evening, do this; Make the movie clip you desire WITHOUT any of the looping, and/or the new MC. This is next. Then when you have what you desire, go to the frame you want to have the MC start on inside the movie you have completed, and make the MC in that frame. Then INSIDE the new MC make what you need and want to do that loopy thing, then do NOT place a stop at the end or anywhere else INSIDE this new MC. The MC will start with whatever frame you place it and will not stop and will loop until the cows come home or we lose electricity from a nuclear blast; Doh!
Hope this was clear; Im sure we will find out if it wasn’t!