I've had V7b crash twice on me in the last hour or so.
Once when I inadvertently selected the WAX plugin for a transition. An "empty" VideoFX window appeared, a brief message saying "Wax does not work with this version of Vegas" (Then why was it in my FX menu?), then "Program Not Resonding." Restart required.
Later, I had an image on the timeline. Selected it. Ctrl-C to copy. Ctrl-V to paste. D'oh. "Program Not Responding". Restart required.
This (the latter crash, at least) never happened with V6.
My question is a general one. Have you found V7 to be more, or less, stable than V6?