This has happened to me on other projects. I have a project I am working on now. When I open the project it shows that I am using about 4gb of ram in the task manager for Blender. Now as work I along the ram meter will start climbing and with in minutes my 20 Gig of ram is all used up. So I have to close Blender. Is this a memory leak? Now rendering, just while I am modeling, texturing and moving things around.
I am using 2.68a win7 x64