I see this thread is from 2013, it is now 2016, I have the exact same issue or similar. CRASH when closing the HTML page. Now I have narrowed it down to that DW crashes when you view the DEsign view of a responsive web page that calls CSS that is responsive, and if you have open the CSS designer panel, Design view, then close that HTML page, it crashes every time!!!!
Also it crashes same as above but if you also have CSS Designer panel open, Design view of the web page, then F10 to view CODE view, then close HTML page. Boom.... CRASH. This is not our websites, not our code it is DW problem!
Also with the tests above, ... you can re-create it by creating a NEW web page, pick the responsive web page that Adobe gives you with DW, create that HTML page. It then creats the small assets folders that include a CSS file with Media Query in it... then do the tests above and it will crash. So it is not a specific website I built or others built, it even crashes using a simple web page created by Dreamweaver!!