Does the animation have more than 16000 frames in it? If so, it's likely to be the cause of the freeze. (And if it does at 2 minutes, may I ask are you making the animation at 120 fps? That's a bit too high...)
To solve that problem, can you break your movie into parts? You can, for example, break it into 10 parts each having about a minute, and load the next movie at the end of each part.
To load movies with AS3, see:
Oh, I misread the 2 minutes thing. But yeah, the frame limit is probably the reason.
For more about Flash and the limit of 16000, see this: http://helpx.adobe.com/flash/kb/flash-movie-size-limit-flash.html
The canvas size limit will be lifted to 8192*8192 in Flash CS6; I don't know if other limitations will change.