Wow, didn’t mean to ruffle any feathers, I’m very new to the software, and didn’t know what information would be useful. I am running a MAC OS X Snow Leopard Version 10.6.6 with a 2×2.4 GHz Quad-Core Intel Xeon, and 12 GB of RAM. I am using AE CS4 version 9.0.3. I am creating an idea of moving quickly through space, there are multiple layers in the composition, but I only want to apply the Motion Blur to 2 layers, both solids using particle world, and both the same size 720X480. Both of the tips that you gave, which I really appreciate, both have already been turned off. I had to do that in order to use particle world in the first place. Do you think it’s possible that the program is having trouble being compatible with the new operating system. I have noticed there there are continuing problems with that. Thank you for your time.. I am very very new to this, and I don’t know anyone that can help, and I can’t seem to find anything on the internet about this issue.