The Problem with Snowflakes 2.0

Just completed the tut on snowflakes 2.0, but when i publish preview i only get this error msg -

“a script in this movie is causing flash to run slowly, your computer may become un-responsive, do you want to abort the script?”

in the tut it says that 75 movie clips are replecated to create the effect, i thought i’d lower the amount and that would slove the problem, (even down to just 2) but the same message occurs.

any ideas?