OK, thanks for the stack traces everyone, looks like the same issue. I suspect this is an OpenGL driver issue which is why I can't reproduce it.
There's a new diagnostic build here
(previous links are dead now). The reason it crashed before was an unhandled exception being thrown from the renderer - I've changed this for asserts so you should see a check failure instead of a crash. If you get a check failure, paste it here, and click ignore - hopefully you can ignore it and it won't crash. If that seems reliable, I'll just turn off the checks. If it still crashes, a stack trace will be handy again.
Thanks everyone, this is a really difficult bug, but we'll get to the bottom of it!