Have you installed the After Effects CS5 (10.0.1) update? That update fixes a lot of problems.
If installing that update doesn't solve the problem, then try this: Remove the Mthread plug-in before starting After Effects (e.g., by dragging the plug-in to the desktop). The plug-in is in the following folder: Applications/Adobe After Effects CS5/Plug-ins/Extensions
Thanks! The update seemed to fix it
.... Wait. Now it isn't working.
It worked for my first solid, but now I want to make another. Now the same error appears.....
I have the update, and also have removed that plugin you said.
Exactly the same happens to me. I'm on the new Macbook Pro. The color picker crashes AE
Any solutions on this?