I think that this is a problem with Adobe CS4 and the new Flash Player, and I think it centers around the clipboard memory. I think what is going on is that there is a shared clipboard, however the owner of that memory is undefined according to the console (OSX). I suspect that Adobe has created a shared clipboard space between its applications and the interaction with the recent flashplayer is causing ownership issues.
The error happens when a CS4 app (possibly CS5, untested with me) quits. I assume it checks to see if other CS apps are running; if not it releases the memory that the clipboard uses. With the new update to flash player, it appears to the OS that dreamweaver is releasing memory it was not allocated; This is a security problem from the perspective of the kernel.
Just a theory, the only fix will be with adobe, I suspect.