Strange patches appearing over PNGs

I'm putting together a flash animation which has 1 png file replicated quite a few times. to be more precise, a snow flake. When they build up on top of each other im getting strange blotches that should not be there.
I have a feeling that because of how many times the image is replicated it is struggling (Flash, not my computer), as when there were only half of the flakes it did not do it.
Please take a look at the jpg for a better understanding, and hopefully someone may have an answer or solution.