For the past couple days I have been getting a rather annoying popup box that says I am running low on memory, and that Dreamweaver suggests I save my work and restart the computer. I don't recall the exact message, but it is pretty similar to what's above.
I was using about 1gb out of the 4gb of ram when I got that error message. Hard drive still has plenty of space.
If you still get the problem then look in the processes and make sure there's only one dreamweaver running. It has a habit of staying in memory when you close it and loading a new one if you open it again.