I am working with Adobe Flash Proffesional CS4 and I have a lot of items in the library. When I try to put another piece of art, such as a PNG, a JPG, or any other format, the program stops letting me interact with it, making that generic microsoft "ding" and the Library stays at that outlined green as if it's still waiting for the art to be put in there. I end up having to close Flash by using Task Manager. I can save the file, but when I go back to it, the PNG I put in there is no longer there.
I am having the same issue with Flash CS4. Did you find a solution?