Instant crash when converting bitmap to symbol.

This problem has been random in the past, but is now permanent. I'm saving a PNG with alpha from LightWave 3D. I'm using Flash CS4 10.0.2 and have the latest updates installed. Flash crashes immediately upon trying to convert the imported bitmap PNG to a symbol. I've tried opening the PNG in Fireworks and saving it under a new name, same problem. Any clues would be appreciated.

Edit: And to be even more arbitrary, I can convert the bitmap in Flash 8 and import the symbol to Flash CS4 and it works fine.