If it crashes when you open the swf file up, add an extra swf frame and import it into flash and re-export it from there. Not only does it compress it somemore, but it solve any issues.
If it doesn't import well... Macro Flash (or whatever software you're using) crashes, export the MoHo file layer by layer, 149 frames at a time (or however many frames suits your need). so you would export 1-150 then 151-300 etc... Re-import this into your flash editing program and link it all up and re-export.
If MoHo crashes upon export, it can mean a number of things, some of them us, the users, haven't quite discovered.
I know there's a a max image and vector (or anything on stage) limit. Try and keep images under 3000x3000 if possible and also make sure you're backgrounds don't over go this.
You might find that your background is safe, until you zoom in and the area becomes alot larger and wider etc. Basically to solve this resize your background to the min zoom area of your project (so it barely fits within your project area boarder thing) and try exporting again.
If all else fails, export layer by layer and then you'll see what the problem is. Tell us if any of this helps/works.
Cheers